blocking navigation from page script

block_navigation.js

var block_navigation = function(state) {
	if (state) {
		window.onbeforeunload = function(e) {
			// If we haven't been passed the event get the window.event
			e = e || window.event;
			var message = 'Any text will block the navigation and display a prompt';
			// For IE6-8 and Firefox prior to version 4
			if (e) { e.returnValue = message; }
			// For Chrome, Safari, IE8+ and Opera 12+
			return message;
		};
	} else {
		window.onbeforeunload = null
	}
};