clicked-outside.js

/**
 * Detect a click outside of an element and run a callback function.
 *
 * @function clickedOutside
 * @param {!Element} element - The element for which to detect an outside click.
 * @param {!Function} callback - The callback function to run when a click outside is detected.
 *
 * @example
 *
 *     clickedOutside(document.getElementById('foo'), function(e) {
 *         console.log('Clicked outside!');
 *     });
 */
function clickedOutside(element, callback) {
    document.addEventListener('click', function(event) {
        var targetElement = event.target;

        do {
            if (targetElement == element) {
                // Clicked inside! Do nothing, just return.
                return;
            }

            // Go up the DOM.
            targetElement = targetElement.parentNode;
        } while (targetElement);

        callback();
    });
}