对HTML属性进行转义。

function esc_attr( $text ) {
	$safe_text = wp_check_invalid_utf8( $text );
	$safe_text = _wp_specialchars( $safe_text, ENT_QUOTES );
	/**
	 * Filters a string cleaned and escaped for output in an HTML attribute.
	 *
	 * Text passed to esc_attr() is stripped of invalid or special characters
	 * before output.
	 *
	 * @since 2.0.6
	 *
	 * @param string $safe_text The text after it has been escaped.
	 * @param string $text      The text prior to being escaped.
	 */
	return apply_filters( 'attribute_escape', $safe_text, $text );
}