class-login-designer-toggle-control.php

<?php
/**
 * Toggle Customizer Control
 */

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

// Exit if WP_Customize_Control does not exsist.
if ( ! class_exists( 'WP_Customize_Control' ) ) {
	return null;
}

/**
 * This class is for the toggle control in the Customizer.
 *
 * @access public
 */
class Login_Designer_Toggle_Control extends WP_Customize_Control {

	/**
	 * The type of customize control.
	 *
	 * @access public
	 * @since  1.3.4
	 * @var    string
	 */
	public $type = 'toggle';

	/**
	 * Enqueue scripts and styles.
	 *
	 * @access public
	 * @since  1.0.0
	 * @return void
	 */
	public function enqueue() {
		wp_enqueue_style( 'login-designer-toggle-control-styles', get_parent_theme_file_uri( 'customizer-controls/toggle/toggle.css' ), false, '1.0.0', 'all' );
		wp_enqueue_script( 'login-designer-toggle-control-scripts', get_parent_theme_file_uri( 'customizer-controls/toggle/toggle.js' ), array( 'jquery' ), '1.0.0', true );
	}

	/**
	 * Add custom parameters to pass to the JS via JSON.
	 *
	 * @access public
	 * @since  1.0.0
	 * @return void
	 */
	public function to_json() {
		parent::to_json();

		// The setting value.
		$this->json['id']           = $this->id;
		$this->json['value']        = $this->value();
		$this->json['link']         = $this->get_link();
		$this->json['defaultValue'] = $this->setting->default;
	}

	/**
	 * Don't render the content via PHP.  This control is handled with a JS template.
	 *
	 * @access public
	 * @since  1.0.0
	 * @return void
	 */
	public function render_content() {}

	/**
	 * An Underscore (JS) template for this control's content.
	 *
	 * Class variables for this control class are available in the `data` JS object;
	 * export custom variables by overriding {@see WP_Customize_Control::to_json()}.
	 *
	 * @see    WP_Customize_Control::print_template()
	 *
	 * @access protected
	 * @since  1.3.4
	 * @return void
	 */
	protected function content_template() {
		?>
		<label class="toggle">
			<div class="toggle--wrapper">

				<# if ( data.label ) { #>
					<span class="customize-control-title">{{ data.label }}</span>
				<# } #>

				<input id="toggle-{{ data.id }}" type="checkbox" class="toggle--input" value="{{ data.value }}" {{{ data.link }}} <# if ( data.value ) { #> checked="checked" <# } #> />
				<label for="toggle-{{ data.id }}" class="toggle--label"></label>
			</div>

			<# if ( data.description ) { #>
				<span class="description customize-control-description">{{ data.description }}</span>
			<# } #>
		</label>
		<?php
	}
}

customizer.php

<?php
/**
 * Customizer.
 *
 * @param WP_Customize_Manager $wp_customize the Customizer object.
 */
function login_designer_customize_register( $wp_customize ) {

  // Add custom control.
  require get_parent_theme_file_path( 'customizer-controls/toggle/class-login-designer-toggle.php' );
  
  // Register the custom control type.
  $wp_customize->register_control_type( 'Login_Designer_Toggle_Control' );
  
  // Add an option to disable the logo.
  $wp_customize->add_setting( 'login_designer[disable_logo]', array(
    'default'           => false,
    'type'              => 'option',
    'transport'         => 'postMessage',
    'sanitize_callback' => 'login_designer_sanitize_checkbox',
  ) );

  $wp_customize->add_control( new Login_Designer_Toggle_Control( $wp_customize, 'login_designer[disable_logo]', array(
    'label'       => esc_html__( 'Enable Logo', 'login-designer' ),
    'section'     => 'login_designer__section--styles',
    'type'        => 'toggle',
    'settings'    => 'login_designer[disable_logo]',
  ) ) );
}

sanitization.php

<?php
/**
 * Checkbox sanitization callback example.
 *
 * Sanitization callback for 'checkbox' type controls. This callback sanitizes `$checked`
 * as a boolean value, either TRUE or FALSE.
 *
 * @param bool $checked Whether the checkbox is checked.
 * @return bool Whether the checkbox is checked.
 */
function login_designer_sanitize_checkbox( $checked ) {
	// Boolean check.
	return ( ( isset( $checked ) && true === $checked ) ? true : false );
}

toggle.css

.customize-control-toggle .toggle--wrapper {
	display: -webkit-box;
	display: -webkit-flex;
	display: -ms-flexbox;
	display: flex;
	flex-direction: row;

	-webkit-box-direction: normal;
	-webkit-box-orient: horizontal;
	-webkit-box-pack: start;
	-webkit-flex-direction: row;
	-ms-flex-direction: row;
	-ms-flex-pack: start;
	-webkit-justify-content: flex-start;
	justify-content: flex-start;
}

.customize-control-toggle .toggle--wrapper .customize-control-title {
	font-weight: 400;
	margin-bottom: 7px;
	vertical-align: middle;
	-webkit-box-flex: 2;
	-webkit-flex: 2 0 0;
	-ms-flex: 2 0 0;
	flex: 2 0 0;
}

.customize-control-toggle .toggle--wrapper input[type=checkbox] {
	display: none;
}

.customize-control-toggle {
	margin-bottom: 0
}

.customize-control-toggle .toggle--wrapper label {
	background-color: #555d66;
	border-radius: 14px;
	cursor: pointer;
	display: inline-block;
	height: 20px;
	outline: none;
	position: relative;
	right: 0px;
	top: 2px;
	-webkit-transition: background 0.2s ease;
	transition: background 0.2s ease;
	-webkit-user-select: none;
	-moz-user-select: none;
	-ms-user-select: none;
	user-select: none;
	width: 34px;
}

.customize-control-toggle .toggle--wrapper label::after,
.customize-control-toggle .toggle--wrapper label::before {
	content: "";
	display: block;
	position: absolute;
}

.customize-control-toggle .toggle--wrapper label::after {
	border: 2px solid #555d66;
	border-radius: 50%;
	box-sizing: border-box;
	height: 12px;
	left: 4px;
	top: 4px;
	-webkit-transition: background 0.2s ease, -webkit-transform 0.2s ease;
	transition: background 0.2s ease, -webkit-transform 0.2s ease;
	transition: transform 0.2s ease, background 0.2s ease;
	transition: transform 0.2s ease, background 0.2s ease, -webkit-transform 0.2s ease;
	width: 12px;
}

.customize-control-toggle .toggle--wrapper label::before {
	background-color: #eee;
	border-radius: 60px;
	bottom: 2px;
	left: 2px;
	right: 2px;
	top: 2px;
	-webkit-transition: background 0.2s ease;
	transition: background 0.2s ease;
}

.customize-control-toggle .toggle--wrapper input[type=checkbox]:checked + label {
	background-color: #0085ba;
}

.customize-control-toggle .toggle--wrapper input[type=checkbox]:checked + label::after {
	background-color: #0085ba;
	border: 2px solid #fff;
	-webkit-transform: translateX(14px);
	-ms-transform: translateX(14px);
	transform: translateX(14px);
}

.customize-control-toggle .toggle--wrapper input[type=checkbox]:checked + label::before {
	background-color: #0085ba;
}

.customize-control-toggle:hover .toggle--wrapper label::before {
	background-color: #d9dcdf;
}

toggle.js

( function( $, api ) {

	api.controlConstructor['toggle'] = api.Control.extend( {

		ready: function() {
			var control = this;

			this.container.on( 'change', 'input:checkbox', function() {
				value = this.checked ? true : false;
				control.setting.set( value );
			} );
		}
   
	} );

} )( jQuery, wp.customize );

It does not save to the database