From 3a3339f90fb8df3aa2b2a748cb04b284e77ea12a Mon Sep 17 00:00:00 2001
From: Dan Remollino <dan@danremollino.dev>
Date: Wed, 2 Apr 2025 16:00:51 -0400
Subject: [PATCH] initial commit

---
 README.md     | 463 ++++++++++++++++++++++++++++++++++++++++++++++++++
 validation.js | 450 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 913 insertions(+)
 create mode 100644 README.md
 create mode 100644 validation.js

diff --git a/README.md b/README.md
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+# Form Validation
+
+Importing the `Validation` class queries the current page for `<form>` elements
+and disables the default browser [constraint validation](https://developer.mozilla.org/en-US/docs/Web/HTML/Constraint_validation)
+by adding a `novalidate` attribute to that element.
+
+The default behavior is to validate each field when their value is updated,
+and validate the entire form when it is submitted. This can be changed to only
+validate on form submission by setting [`onlyOnSubmit`](#onlyonsubmit) to `true` on the
+instance.
+
+Once a field is marked invalid, it will always re-validate when its value is
+changed regardless of the [`onlyOnSubmit`](#onlyOnSubmit) value.
+
+> `required` fields are tested for blank first. If this check is passed, the
+field will then test for [custom rules](#custom-validation) if present. If
+there are no custom rules, some fields are also tested further based on their
+`type` attribute value. These are described [below](#markup).
+
+## Required Fields
+
+Usually, the majority of fields in a form need validation. To make setup
+easier, instances of the *Validation* class have a default [`reqAll`](#reqall)
+value of `true`. This marks all fields that meet the following criteria
+required and needing validation:
+
+* Have a `name` attribute.
+* Not [`disabled`](https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/disabled).
+
+Indivudual fields can then be excluded from validation as described [below](#reqall).
+
+This functionality can be inverted by setting [`reqAll`](#reqall) to `false`,
+and manually giving your required fields a [`required`](https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/required)
+attribute.
+
+```html
+<div class="form-group">
+    <label for="text">Text</label>
+    <input required id="text" type="text" name="text">
+</div>
+```
+
+`<input>` `type` attribute values of `checkbox` and `radio` only need one option to have the
+`required` attribute, however, it is recommended to add it to all options for
+consistency. More information on checkbox and radio fields can be found [below](#checkbox-and-radio-fields).
+
+### Required Indicator
+
+A `<span>` tag with class of `required__indicator` containing an asterisk(*)
+character will be inserted [`beforeend`](https://developer.mozilla.org/en-US/docs/Web/API/Element/insertAdjacentHTML#beforeend)
+of a required field's `<label>` element.
+
+This indicator will be inserted to the `<legend>` element of `checkbox` and
+`radio` `<input>` types if present as described [below](#checkbox-and-radio-fields).
+
+The indicator can be disabled or customized as described in [Form Options](#form-options).
+
+## Markup
+
+The `Validation` class requires the following for each required field:
+- All form fields to be wrapped in an element with the `form-group` class.
+- Do **NOT** nest the required field in a `<label>` element.
+- Unique, matching values of the required field's `id` and its `<label>`'s `for`
+attribute.
+- A unique `name` attribute on the required field. `checkbox` and `radio`
+`<input>` types should share the same unique `name` attribute.
+
+> When a field fails validation the wrapper `.form-group` element will receive
+an `invalid` CSS class. Use this to write your own CSS to indicate an invalid
+state.
+
+```html
+<div class="form-group">
+    <label for="text">Text</label>
+    <input id="text" type="text" name="text">
+</div>
+```
+
+### Checkbox and Radio Fields
+
+- Wrap all options in a `<fieldset>` element and add the `form-group` class to
+it instead of the individual options.
+- The `<legend>` tag may be used to give the option set a heading.
+- Each `checkbox` or `radio` `<input>` type should be wrapped in a
+`form-group__item` class. This class is not used programattically, and is only
+used for styling.
+
+```html
+<fieldset class="form-group">
+    <legend>Check Group</legend>
+    <span class="form-group__item">
+        <input id="checkbox-1" type="checkbox" name="checks">
+        <label for="checkbox-1">Checkbox 1</label>
+    </span>
+    <span class="form-group__item">
+        <input id="checkbox-2" type="checkbox" name="checks">
+        <label for="checkbox-2">Checkbox 2</label>
+    </span>
+</fieldset>
+```
+
+### Select Fields
+
+Required `<select>` elements should contain an `<option>` with the `selected`
+attribute and an empty `value` attribute. If not present the element will pass
+validation even while being required.
+
+```html
+<div class="form-group">
+    <label for="select">Select</label>
+    <select id="select" name="select">
+        <option selected value="">Choose an Item</option>
+        <option>1</option>
+        <option>2</option>
+        <option>3</option>
+    </select>
+</div>
+```
+
+### Password Fields
+
+When an `<input>` element with a `type` attribute of `password` is detected on the
+page, a required *Password Confirm* field will auto generate after its parent
+`.form-group` wrapper.
+
+The markup for this field is a duplicate of the original input's parent
+`.form-group` wrapper. The `id` and `name` attributes of the `<input>` element,
+and the `for` attribute of the `<label>` element will have their values set to
+`password-confirm`.
+
+This functionality can be disabled by settting [`passConfirm`](#passConfirm) to `false`.
+
+A *Password* field with the markup of
+
+```html
+<div class="form-group">
+    <label for="password">Password</label>
+    <input id="password" type="password" name="password">
+</div>
+```
+
+will generate a *Password Confirm* field with the markup of
+
+```html
+<div class="form-group">
+    <label for="password-confirm">Password Confirm<span class="required__indicator">*</span></label>
+    <input id="password-confirm" type="password" name="password-confirm">
+</div>
+```
+
+> The *Password* field is tested that it matches its corresponding
+*Password Confirm* field when the *Password Confirm* field contains a non-blank
+value.
+<br><br>
+The *Password Confirm* field is always tested that it matches its corresponding
+*Password* field.
+
+## Custom Form Controls
+
+[Custom form controls](https://developer.mozilla.org/en-US/docs/Learn_web_development/Extensions/Forms/How_to_build_custom_form_controls)
+can be validated by informing the ValidationField class what you want to check
+against as the value for your control. You can determine validity based on:
+
+1. [Existence of an element.](#existence-of-an-element)
+2. [TextContent of an element.](#textcontent-of-an-element)
+3. [Existence of an attribute.](#existence-of-an-attribute)
+4. [Value of an attribute.](#value-of-an-attribute)
+
+To validate a custom form control, add a `data-validation` attribute to an
+element of the control. The value should be a single quoted JSON object with
+`valueSrc` as a property.
+
+> The element that the `data-validation` attribute is added to **MUST** have a
+unique `id` and `name` attribute. Having an associated `label`/`legend` tag
+with a `for` attribute is optional, but recommended.
+
+The value of the property should be an array with up to three items.
+
+`valueSrc[0]:` A CSS selector to target the element to reference for value.<br>
+`valueSrc[1]:` The keyword `attribute`, `attributeValue`, `exists`, or
+`textContent`.<br>
+`valueSrc[2]:` If using `attribute` or `attributeValue`, the attribute to
+reference. If using `exists`, a CSS selector relative to `valueSrc[0]` as the
+parent.
+
+`valueSrc` can be combined with [`pattern`](#pattern) and [`patternMessage`](#patternmessage)
+field options to check for specific values and output custom error messages.
+See the examples below.
+
+### Existence of an Element
+
+Determine validity based on whether an element exists or not.
+
+*Valid if...* the target element exists.
+
+The following example checks for the presence of in image element that is a
+child of the element with an id of 'custom-control'.
+
+```html
+<div class="form-group">
+    <label for="custom-control">Custom Form Control</label>
+    <div data-validation='{"valueSrc": ["#custom-control", "exists", "img"]}' id="custom-control" name="custom_control"></div>
+</div>
+```
+
+> The third item in the `valueSrc` array can be any valid CSS selector string
+that [`querySelector`](https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector)
+can parse. e.x. `:scope > img`
+
+### TextContent of an Element
+
+Use the target element's [`textContent`](https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent)
+to determine validity. Useful when using [`contenteditable`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/contenteditable).
+
+*Valid if...* the target element's textContent property is a non-empty string.
+
+The following example checks if the element with an id of 'custom-control' has
+a non-empty string [`textContent`](https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent)
+property.
+
+```html
+<div class="form-group">
+    <label for="custom-control">Custom Form Control</label>
+    <div data-validation='{"valueSrc": ["#custom-control", "textContent"]}' id="custom-control" name="custom_control" contenteditable></div>
+</div>
+```
+
+### Existence of an Attribute
+
+Use the target element's specified attribute existence to determine validity.
+
+*Valid if...* the target element's specified attribute exists.
+
+The following example checks if the element with an id of 'custom-control' has
+a `title` attribute.
+
+```html
+<div class="form-group">
+    <label for="custom-control">Custom Form Control</label>
+    <div data-validation='{"valueSrc": ["#custom-control", "attribute", "title"]}' id="custom-control" name="custom_control"></div>
+</div>
+```
+
+> The value of a [boolean attribute](https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML)
+will evaluate as `false` and invalid unless it is a non-empty string. When
+using this option, the attribute must use the `checked="checked"` (true, valid)
+and `checked=""` (false, invalid) form and not `checked`. `checked` will
+evaluate as false and invalid whether present or not.
+
+### Value of an Attribute
+
+Use the target element's specified attribute value to determine validity.
+
+*Valid if...* the value of the target's specified attribute is a non-empty string.
+
+The following example checks if the element with an id of 'custom-control' has
+a `title` attribute with a non-empty string value.
+
+```html
+<div class="form-group">
+    <label for="custom-control">Custom Form Control</label>
+    <div data-validation='{"valueSrc": ["#custom-control", "attributeValue", "title"]}' id="custom-control" name="custom_control"></div>
+</div>
+```
+
+> The value of a [boolean attribute](https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML)
+will evaluate as `false` and invalid unless it is a non-empty string. When
+using this option, the attribute must use the `checked="checked"` (true, valid)
+and `checked=""` (false, invalid) syntax. If you need to check a boolean
+attribute use [`attribute`](#existence-of-an-attribute).
+
+## Form Options
+
+* [invalidClass](#invalidclass)
+* [messageClass](#messageclass)
+* [onlyOnSubmit](#onlyonsubmit)
+* [onSuccess](#onsuccess)
+* [passConfirm](#passconfirm)
+* [reqAll](#reqall)
+* [reqIndicator](#reqindicator)
+* [reqIndicators](#reqindicators)
+* [reqIndicatorClass](#reqindicatorclass)
+* [valFieldsOn](#valfieldson)
+
+Default instance options can be overwritten by adding a single quoted
+`data-validation` attribute on the `<form>` being validated. Its value must be
+a properly formatted JSON object.
+
+```html
+<form data-validation='{"onlyOnSubmit": true, "reqIndicator": "❗️"}'>
+    <div class="form-group">
+        <label for="text">Text</label>
+        <input id="text" type="text" name="text">
+    </div>
+    <div class="form-group">
+        <button type="submit">Submit</button>
+    </div>
+</form>
+```
+
+### invalidClass
+
+**Default:** `invalid`
+
+The class assigned to the parent `<div class="form-group" />` wrapper of the
+invalid field.
+
+### messageClass
+
+**Default:** `invalid__message`
+
+The class assigned output message of the invalid field.
+
+### onlyOnSubmit
+
+**Default:** `false`
+
+Only validate the form on submission. A setting of `true` will disable
+individual field validation. Regardless of this setting fields will always
+validate on the [`valFieldsOn`](#valFieldsOn) value while they are invalid.
+
+### onSuccess
+
+**Default:** `null`
+
+Run a script when the form is submited and all fields pass validation. A non
+truthy value will cancel the form's default action.
+
+```html
+<form data-validation='{"onSuccess": "save()"}'>...</form>
+```
+
+### passConfirm
+
+**Default:** `true`
+
+Automatically create a confirm password field. The markup from the user created
+field with a `type="password"` attribute will be duplicated and modifed, then
+inserted after the original field.
+
+```html
+<form data-validation='{"passConfirm": true}'>...</form>
+```
+
+### reqAll
+
+**Default:** `true`
+
+Automatically add a `required` attribute to all `<input>`, `<select>`, and
+`<textarea>` tags in the `<form>`. This allows you to skip marking individual
+fields as `required` in your markup.
+
+> Individual fields can be excluded from validation by adding a
+`data-validation` attribute to a field that's value is a JSON object with an
+[`optional`](#optional) property value set to `true`.
+
+```html
+<div class="form-group">
+    <label for="not-required">Not Required</label>
+    <input data-validation='{"optional": true}' id="not-required" type="text" name="not_required">
+</div>
+```
+
+### reqIndicator
+
+**Default:** `*`
+
+The string to render after the label text to indicate to the user that the
+field is required.
+
+### reqIndicators
+
+**Default:** `true`
+
+Enable the output of `reqIndicator` strings.
+
+If set to `false`, you can target all field labels with the CSS selector below
+to apply a custom style.
+
+```css
+.form-group:has([required])
+:where(label:has(:not(.form-group__item)), legend) {
+    /* Your styles here. */
+}
+```
+
+### reqIndicatorClass
+
+**Default:** `required__indicator`
+
+The class assigned to the `<span>` wrapper of the outputted `reqIndicator`.
+
+### valFieldsOn
+
+**Default:** `input`
+
+The event that triggeers individual field validation. Value can be any
+JavaScript event, but it is recommended to try
+[`blur`](https://developer.mozilla.org/en-US/docs/Web/API/Element/blur_event),
+[`change`](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/change_event),
+or [`input`](https://developer.mozilla.org/en-US/docs/Web/API/Element/input_event).
+
+> Individual field validation can be disable by setting
+[`onlyOnSubmit`](#onlyOnSubmit) to true.
+
+## Field Options
+
+* [optional](#optional)
+* [pattern](#pattern)
+* [patternMessage](#patternmessage)
+* [valueSrc](#valuesrc)
+
+Individual fields can be passed options to customize their behavior by adding a
+single quoted `data-validation` attribute to a field. Its value must be a
+properly formatted JSON object with the properties and values below.
+
+```html
+<div class="form-group">
+    <label for="custom">Custom Regex</label>
+    <input data-validation='{"optional": true,
+                             "pattern": "^[0-9]*$",
+                             "patternMessage": "This field must only contain numbers."
+                            }'
+           id="custom" type="text" inputmode="numeric" name="custom">
+</div>
+```
+
+### optional
+
+**Default:** `false`
+
+Fields with the `optional` property set to `true` will pass vaidation when
+blank. They still will be processed for validation when they contain a value
+based on the `input` `type` attribute, or if a user [`pattern`](#pattern) is specified.
+
+### pattern
+
+**Default:** `null`
+
+A regular expression to test the field's value against. This string is also
+copied and added to the field as a native [`pattern`](https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/pattern)
+attribute. It is recommended to also provide an error message to display when
+the value does not match `pattern` by providing a [`patternMessage`](#patternmessage).
+
+> The pattern is checked when input is present. A required field will always
+first test for blank, then for the provided pattern.
+
+### patternMessage
+
+**Default:** `null`
+
+An error message to display when the field fails the custom validation test
+provided by [`pattern`](#pattern).
+
+> If not provided with [`pattern`](#pattern) the field will be marked as
+invalid, but no message will output when the pattern does not match.
+
+### valueSrc
+
+**Default:** `null`
+
+Used to validate [custom form controls](https://developer.mozilla.org/en-US/docs/Learn_web_development/Extensions/Forms/How_to_build_custom_form_controls).
+See [here](#custom-form-controls) for more information.
diff --git a/validation.js b/validation.js
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+++ b/validation.js
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+class ValidationField {
+    el = null
+    formGroupEl = null
+    isValid = null
+    labelEl = null
+    labelText = null
+    message = null
+    messageOutputted = null
+    optional = false
+    pattern = null
+    patternMessage = null
+    validationInstance = null
+    valueSrc = [] // [css_selector, 'attribute|attributeValue'|'exists'|'textContent', attribute_name|element]
+
+    constructor(obj) {
+        try {
+            Object.assign(this, obj)
+
+            this.formGroupEl = this.el.closest('.form-group')
+            this.labelEl = this.formGroupEl?.querySelector('legend') ??
+                        this.validationInstance.form.querySelector(
+                            `[name="${this.el.getAttribute('name')}"]:not([type="hidden"])`
+                        ).closest('.form-group').querySelector('label')
+            this.labelText = this.labelEl?.textContent.replace(this.validationInstance.reqIndicator, '')
+
+            // user field config
+            try {
+                Object.assign(this, this.el.dataset.validation ? JSON.parse(this.el.dataset.validation) : {})
+            } catch(error) {
+                if (error instanceof SyntaxError) {
+                    console.warn(`There was a problem configuring your field options. Using defaults. Are you using a properly formatted JSON object? (e.g. data-validation='{"optional": true}')\n\nElement: ${this.el.outerHTML}`)
+                }
+                delete this.el.dataset.validation
+            }
+
+            // custom form controls
+            if (this.valueSrc.length > 0) {
+                const valueProps = {
+                    valueRef: this.validationInstance.form.querySelector(this.valueSrc[0]),
+                    kind: this.valueSrc[1],
+                    attr: this.valueSrc[2]
+                }
+
+                let observerOpts
+                const updateValue = (valueProps) => {
+                    switch (valueProps.kind) {
+                        case 'attribute':
+                            valueProps.valueRef.hasAttribute(valueProps.attr)
+                                ? this.el.setAttribute('value', '1')
+                                : this.el.setAttribute('value', '')
+                                observerOpts = {attributeFilter: [valueProps.attr]}
+                            break
+                        case 'attributeValue':
+                            valueProps.valueRef.getAttribute(valueProps.attr)
+                                ? this.el.setAttribute('value', valueProps.valueRef.getAttribute(valueProps.attr))
+                                : this.el.setAttribute('value', '')
+                                observerOpts = {attributeFilter: [valueProps.attr]}
+                            break
+                        case 'exists':
+                            valueProps.valueRef.querySelector(valueProps.attr)
+                                ? this.el.setAttribute('value', '1')
+                                : this.el.setAttribute('value', '')
+                                observerOpts = {childList: true}
+                            break
+                        case 'textContent':
+                            this.el.setAttribute('value', valueProps.valueRef?.textContent.trim())
+                            observerOpts = {characterData: true, childList: true, subtree: true}
+                            break
+                    }
+                }
+
+                updateValue(valueProps)
+
+                const custConObserver = new MutationObserver((mutationList, observer) => {
+                    updateValue(valueProps)
+                    this.validationInstance.validate(this)
+                })
+
+                custConObserver.observe(valueProps.valueRef, observerOpts)
+
+                // focus on the value target when the label is clicked
+                this.labelEl.addEventListener('click', () => {
+                    valueProps.valueRef.focus()
+                })
+            }
+
+            // validate individual fields according to the parent Validation
+            // instance `valFieldsOn` value
+            this.el.addEventListener(this.validationInstance.valFieldsOn, () => {
+                this.validationInstance.validate(this)
+            })
+
+            // add a native pattern attr if pattern property is present
+            if (this.pattern) this.el.setAttribute('pattern', this.pattern)
+
+            // add required indicator
+            if (this.validationInstance.reqIndicators) {
+                const hasIndicator = this.formGroupEl?.querySelector(`.${this.validationInstance.reqIndicatorClass}`)
+                if (!hasIndicator && !this.optional) {
+                    this.labelEl?.insertAdjacentHTML(
+                        'beforeend',
+                        `<span class="${this.validationInstance.reqIndicatorClass}">${this.validationInstance.reqIndicator}</span>`
+                    )
+                }
+            }
+
+            // validate the field without outputting errors to set the default state
+            this.validationInstance.validate(this, false, true)
+
+            // console.log(this)
+        } catch (error) {
+            console.warn(`Something when wrong setting up a ValidationField instance.`)
+        }
+    }
+}
+
+class Validation {
+    static forms = []
+
+    errors = []
+    form = null
+    invalidClass = 'invalid'
+    messageClass = 'invalid__message'
+    onlyOnSubmit = false
+    onSuccess = null
+    passConfirm = true
+    passConfirmField = null
+    passwordField = null
+    reqAll = true
+    reqIndicator = '*'
+    reqIndicators = true
+    reqIndicatorClass = 'required__indicator'
+    reqData = new Set()
+    reqFields = []
+    valFieldsOn = 'input' // blur, change, input
+
+    constructor(obj) {
+        Object.assign(this, obj)
+
+        // check for custom form controls
+        const custFormControls = this.form.querySelectorAll('[data-validation]:not(form, input, select, textarea)')
+        if (custFormControls.length > 0) {
+            for (const el of custFormControls) {
+                try {
+                    const fieldOptions = JSON.parse(el.dataset.validation)
+                    if (!this.form.querySelector(fieldOptions.valueSrc[0])) {
+                        throw new Error(`No element matched with the supplied selector – ${fieldOptions.valueSrc[0]}`)
+                    }
+
+                    let inputEl = document.createElement('input')
+                    inputEl.dataset.validation = el.dataset.validation
+                    let inputAttrs = {name: el.getAttribute('name'), type: 'hidden', value: ''}
+                    for (const [key, value] of Object.entries(inputAttrs)) {
+                        inputEl[key] = value
+                    }
+
+                    el.parentElement.prepend(inputEl)
+                } catch (error) {
+                    console.warn(`There was a problem configuring your custom form control. Aborted.\n\nError: ${error.message}.\n\nElement: ${el.outerHTML}`)
+                }
+            }
+        }
+
+        // add confirm password field if a password field is present
+        if (this.passConfirm) {
+            const pwField = this.form.querySelector('input[type="password"]')
+            if (pwField) {
+                this.passwordField = new ValidationField({el: pwField, validationInstance: this})
+                const passConfirmGroup = this.passwordField.formGroupEl.cloneNode(true)
+                for (const child of passConfirmGroup.children) {
+                    switch (child.tagName) {
+                        case 'LABEL':
+                            child.innerText = 'Password Confirm'
+                            child.htmlFor = 'password-confirm'
+                            break
+                        case 'INPUT':
+                            child.setAttribute('id', 'password-confirm')
+                            child.setAttribute('name', 'password-confirm')
+                            break
+                    }
+                }
+                this.passwordField.formGroupEl.insertAdjacentHTML('afterend', passConfirmGroup.outerHTML)
+                this.passConfirmField = new ValidationField({el: this.form.querySelector('input[name="password-confirm"]'), validationInstance: this})
+            }
+        }
+
+        // add required attr to fields if reqAll == true
+        if (this.reqAll) {
+            for (const field of this.form.querySelectorAll('input, select, textarea')) {
+                field.setAttribute('required', 'required')
+            }
+        }
+
+        // check for fields that are elidgeable for validation and make a set of unique name attr values
+        for (const field of this.form.querySelectorAll(':where(input, select, textarea)[required][name]:not([disabled])')) {
+            this.reqData.add(field.name)
+        }
+
+        // create a list of all the field elements that were specified for validation
+        for (const nameAttr of this.reqData) {
+            const fields = this.form.querySelectorAll(`[name="${nameAttr}"]:where(input, select, textarea)`)
+            for (const el of fields) {
+                this.reqFields.push(new ValidationField({el: el, validationInstance: this}))
+            }
+        }
+
+        this.form.addEventListener('submit', e => {
+            e.preventDefault()
+            this.validate()
+        })
+
+        this.form.addEventListener('reset', () => {
+            this.removeErrors()
+        })
+
+        // add/remove a field when disabled attr is dynamically toggled
+        const observeEls = this.form.querySelectorAll('input, select, textarea, [data-validation]:not(form, input, select, textarea)')
+        const disabledObserver = new MutationObserver((mutationList, observer) => {
+            for (const item of mutationList) {
+                let updateEl = item.target
+
+                if (item.target.dataset.validation?.includes('valueSrc')) {
+                    // custom form control – update the hidden input instead
+                    updateEl = this.form.querySelector(
+                        `input[name="${item.target.getAttribute('name')}"][type="hidden"]`
+                    )
+                }
+
+                updateEl.hasAttribute('disabled')
+                    ? this.removeField(updateEl)
+                    : this.addField(updateEl)
+            }
+        })
+        for (const el of observeEls) {
+            disabledObserver.observe(el, {
+                attributes: true,
+                attributeFilter: ['disabled'],
+                attributeOldValue: true
+            })
+        }
+
+        // console.log(this)
+    }
+
+    // add a field after initialization
+    addField(el) {
+        this.reqData.add(el.name)
+        this.reqFields.push(new ValidationField({el: el, validationInstance: this}))
+    }
+
+    // remove a field after initialization
+    removeField(el) {
+        this.reqData.delete(el.name)
+        for (const obj of this.reqFields) {
+            if (el === obj.el) {
+                obj.formGroupEl.querySelector(`.${this.reqIndicatorClass}`)?.remove()
+                this.reqFields.pop(obj)
+                this.removeErrors(obj)
+            }
+        }
+    }
+
+    parseField(fieldInstance) {
+        const nameAttrVal = fieldInstance.el.name
+
+        if (!fieldInstance.optional) {
+            if (!fieldInstance.el.value) {
+                this.validateForBlank(fieldInstance)
+            } else {
+                if (fieldInstance.pattern) {
+                    this.validateForPattern(fieldInstance)
+                } else {
+                    switch (fieldInstance.el.type) {
+                        case 'checkbox':
+                            this.validateCheckbox(fieldInstance, nameAttrVal)
+                            break
+                        case 'email':
+                            this.validateEmail(fieldInstance)
+                            break
+                        case 'password':
+                            if (fieldInstance.el.name === 'password') this.validatePassword(fieldInstance)
+                            if (fieldInstance.el.name === 'password-confirm') this.validateConfirmPass(fieldInstance)
+                            break
+                        case 'radio':
+                            this.validateRadio(fieldInstance, nameAttrVal)
+                            break
+                        case 'tel':
+                            this.validateTel(fieldInstance)
+                            break
+                    }
+                }
+            }
+        }
+    }
+
+    validateForBlank(fieldInstance) {
+        this.addError(
+            fieldInstance,
+            (fieldInstance.labelText ? fieldInstance.labelText : `Field`) + ` is required.`
+        )
+    }
+
+    validateForPattern(fieldInstance) {
+        const regex = new RegExp(fieldInstance.pattern)
+        if (!regex.test(fieldInstance.el.value)) {
+            this.addError(fieldInstance, fieldInstance.patternMessage)
+        }
+    }
+
+    validateCheckbox(fieldInstance, nameAttrVal) {
+        if (!this.form.querySelector(`[name="${nameAttrVal}"]:checked`)) {
+            this.addError(fieldInstance, `At least one choice is required.`)
+        }
+    }
+
+    validateEmail(fieldInstance) {
+        const regex = new RegExp(/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/)
+        if (!regex.test(fieldInstance.el.value)) {
+            this.addError(fieldInstance, `'${fieldInstance.el.value}' is not a valid email address.`)
+        }
+    }
+
+    validatePassword(fieldInstance) {
+        if (this.passConfirmField.el.value) {
+            if (this.passConfirmField.el.value !== this.passwordField.el.value) {
+                this.validate(this.passConfirmField)
+            } else {
+                this.removeErrors(this.passConfirmField)
+            }
+        }
+
+        // minimum eight characters, at least one upper case English letter,
+        // one lower case English letter, one number and one special character
+        const regex = new RegExp(/^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$ %^&*-]).{8,}$/)
+        if (!regex.test(fieldInstance.el.value)) {
+            this.addError(fieldInstance, `Password is not secure.`)
+        }
+    }
+
+    validateConfirmPass(fieldInstance) {
+        if (fieldInstance.el.value !== this.passwordField.el.value) {
+            this.removeErrors(fieldInstance)
+            this.addError(fieldInstance, `Does not match Password field.`)
+        }
+    }
+
+    validateRadio(fieldInstance, nameAttrVal) {
+        if (!this.form.querySelector(`[name="${nameAttrVal}"]:checked`)) {
+            this.addError(fieldInstance, `A choice is required.`)
+        }
+    }
+
+    validateTel(fieldInstance) {
+        // 1234567890, 123-456-7890, (123)456-7890, (123) 456-7890
+        const regex = new RegExp(/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/)
+        if (!regex.test(fieldInstance.el.value)) {
+            this.addError(fieldInstance, `'${fieldInstance.el.value}' is not a valid telephone number.`)
+        }
+    }
+
+    addError(fieldInstance, message) {
+        fieldInstance.isValid = false
+        fieldInstance.message = message
+        this.errors.push(fieldInstance)
+    }
+
+    outputErrors(fieldInstance) {
+        for (const error of this.errors) {
+            if (!fieldInstance || error.el === fieldInstance.el) {
+                error.formGroupEl.classList.add(`${this.invalidClass}`)
+                if (error.message) {
+                    error.el.insertAdjacentHTML(
+                        'beforeBegin',
+                        `<div class="${this.messageClass}">${error.message}</div>`
+                    )
+                }
+                error.messageOutputted = true
+            }
+        }
+    }
+
+    removeErrors(fieldInstance) {
+        const updateMarkup = valField => {
+            valField.formGroupEl.classList.remove(`${this.invalidClass}`)
+            valField.formGroupEl.querySelector(`.${this.messageClass}`)?.remove()
+        }
+
+        if (fieldInstance) {
+            for (const [index, error] of this.errors.entries()) {
+                if (error.el.name === fieldInstance.el.name) {
+                    this.errors.splice(index, 1)
+                }
+            }
+            updateMarkup(fieldInstance)
+            fieldInstance.isValid = true
+            fieldInstance.messageOutputted = false
+        } else {
+            for (const error of this.errors) {
+                updateMarkup(error)
+            }
+            this.errors.length = 0
+        }
+    }
+
+    validate(fieldInstance, outputErrors = true, force = false) {
+        if (fieldInstance) {
+            if (!this.onlyOnSubmit || (this.onlyOnSubmit && fieldInstance.messageOutputted) || force) {
+                this.removeErrors(fieldInstance)
+                this.parseField(fieldInstance)
+                if (outputErrors) this.outputErrors(fieldInstance)
+            }
+        } else {
+            if (this.errors.length > 0) this.removeErrors()
+            for (const nameAttrVal of this.reqData) {
+                for (const field of this.reqFields) {
+                    if (field.el.name === nameAttrVal) {
+                        this.parseField(field)
+                        break
+                    }
+                }
+            }
+            this.outputErrors()
+        }
+
+        // console.log(this); return;
+
+        // form was sbmitted and all fields pass validation
+        if (!fieldInstance && this.errors.length === 0) {
+            this.onSuccess ? Function(this.onSuccess)() : this.form.submit()
+        }
+    }
+
+    static {
+        const forms = document.getElementsByTagName('form')
+        for (let form of forms) {
+            form.noValidate = true
+            try {
+                const config = Object.assign(
+                    {form: form},
+                    form.dataset.validation ? JSON.parse(form.dataset.validation) : {}
+                )
+                Validation.forms.push(new Validation(config))
+            } catch(error) {
+                if (error instanceof SyntaxError) console.warn(`There was a problem configuring your custom validation options. Using defaults. Are you using a properly formatted JSON object? (e.g. data-validation='{"reqIndicators": false}')`)
+                delete form.dataset.validation
+                Validation.forms.push(new Validation({form: form}))
+            }
+        }
+    }
+}