Source

File: wp-includes/class-wp-customize-nav-menus.php

public function print_templates() {
		?>
		<script type="text/html" id="tmpl-available-menu-item">
			<li id="menu-item-tpl-{{ data.id }}" class="menu-item-tpl" data-menu-item-id="{{ data.id }}">
				<div class="menu-item-bar">
					<div class="menu-item-handle">
						<span class="item-type" aria-hidden="true">{{ data.type_label }}</span>
						<span class="item-title" aria-hidden="true">
							<span class="menu-item-title<# if ( ! data.title ) { #> no-title<# } #>">{{ data.title || wp.customize.Menus.data.l10n.untitled }}</span>
						</span>
						<button type="button" class="button-link item-add">
							<span class="screen-reader-text">
							<?php
								/* translators: 1: Title of a menu item, 2: Type of a menu item. */
								printf( __( 'Add to menu: %1$s (%2$s)' ), '{{ data.title || wp.customize.Menus.data.l10n.untitled }}', '{{ data.type_label }}' );
							?>
							</span>
						</button>
					</div>
				</div>
			</li>
		</script>

		<script type="text/html" id="tmpl-menu-item-reorder-nav">
			<div class="menu-item-reorder-nav">
				<?php
				printf(
					'<button type="button" class="menus-move-up">%1$s</button><button type="button" class="menus-move-down">%2$s</button><button type="button" class="menus-move-left">%3$s</button><button type="button" class="menus-move-right">%4$s</button>',
					__( 'Move up' ),
					__( 'Move down' ),
					__( 'Move one level up' ),
					__( 'Move one level down' )
				);
				?>
			</div>
		</script>

		<script type="text/html" id="tmpl-nav-menu-delete-button">
			<div class="menu-delete-item">
				<button type="button" class="button-link button-link-delete">
					<?php _e( 'Delete Menu' ); ?>
				</button>
			</div>
		</script>

		<script type="text/html" id="tmpl-nav-menu-submit-new-button">
			<p id="customize-new-menu-submit-description"><?php _e( 'Click &#8220;Next&#8221; to start adding links to your new menu.' ); ?></p>
			<button id="customize-new-menu-submit" type="button" class="button" aria-describedby="customize-new-menu-submit-description"><?php _e( 'Next' ); ?></button>
		</script>

		<script type="text/html" id="tmpl-nav-menu-locations-header">
			<span class="customize-control-title customize-section-title-menu_locations-heading">{{ data.l10n.locationsTitle }}</span>
			<p class="customize-control-description customize-section-title-menu_locations-description">{{ data.l10n.locationsDescription }}</p>
		</script>

		<script type="text/html" id="tmpl-nav-menu-create-menu-section-title">
			<p class="add-new-menu-notice">
				<?php _e( 'It doesn&#8217;t look like your site has any menus yet. Want to build one? Click the button to start.' ); ?>
			</p>
			<p class="add-new-menu-notice">
				<?php _e( 'You&#8217;ll create a menu, assign it a location, and add menu items like links to pages and categories. If your theme has multiple menu areas, you might need to create more than one.' ); ?>
			</p>
			<h3>
				<button type="button" class="button customize-add-menu-button">
					<?php _e( 'Create New Menu' ); ?>
				</button>
			</h3>
		</script>
		<?php
	}