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wp_check_jsonp_callback() WP 4.6.0

Checks that a JSONP callback is a valid JavaScript callback.

Only allows alphanumeric characters and the dot character in callback function names. This helps to mitigate XSS attacks caused by directly outputting user input.

No Hooks.

Return

true/false. True if valid callback, otherwise false.

Usage

wp_check_jsonp_callback( $callback );
$callback(string) (required)
Supplied JSONP callback function.

Code of wp check jsonp callback: wp-includes/functions.php VER 5.0.3

<?php
function wp_check_jsonp_callback( $callback ) {
	if ( ! is_string( $callback ) ) {
		return false;
	}

	preg_replace( '/[^\w\.]/', '', $callback, -1, $illegal_char_count );

	return 0 === $illegal_char_count;
}