Source

File: wp-includes/customize/class-wp-customize-code-editor-control.php

public function content_template() {
		?>
		<# var elementIdPrefix = 'el' + String( Math.random() ); #>
		<# if ( data.label ) { #>
			<label for="{{ elementIdPrefix }}_editor" class="customize-control-title">
				{{ data.label }}
			</label>
		<# } #>
		<# if ( data.description ) { #>
			<span class="description customize-control-description">{{{ data.description }}}</span>
		<# } #>
		<div class="customize-control-notifications-container"></div>
		<textarea id="{{ elementIdPrefix }}_editor"
			<# _.each( _.extend( { 'class': 'code' }, data.input_attrs ), function( value, key ) { #>
				{{{ key }}}="{{ value }}"
			<# }); #>
			></textarea>
		<?php
	}