Perform a window.open, centering it (even for dual monitor setups), and only allow one open instance of each identifier at a time

popwindow.js

/*
	Pops open a new window given the identifier (name), url, width, height, and
	optional additional options (as normally passed to window.open()), centered
	on the screen.  Additionally, it will not open more than one instance of each
	identifier.

	Amalgamation of:
		https://developer.mozilla.org/en-US/docs/Web/API/Window.open "Best Practices"
		http://stackoverflow.com/questions/4068373/center-a-popup-window-on-screen
			"Single/Dual Monitor Function"
		+ Event handler for .popup-window 
	
	- A.B. Carroll <[email protected]>
*/

$(function() {
	$.popWindowReferences = [];
	$.popWindow = function(name, url, w, h, options) {
		var winObjRef = $.popWindowReferences[name];

		if(winObjRef == null || winObjRef.closed) {

			if(typeof options == "undefined") {
				options = "";
			} else {
				options = "," + options;
			}

			// Fixes dual-screen position for most browsers
			var dualScreenLeft = window.screenLeft != undefined ? window.screenLeft : screen.left;
			var dualScreenTop = window.screenTop != undefined ? window.screenTop : screen.top;

			width = window.innerWidth ? window.innerWidth : document.documentElement.clientWidth ? document.documentElement.clientWidth : screen.width;
			height = window.innerHeight ? window.innerHeight : document.documentElement.clientHeight ? document.documentElement.clientHeight : screen.height;

			var left = ((width / 2) - (w / 2)) + dualScreenLeft;
			var top = ((height / 2) - (h / 2)) + dualScreenTop;
			var newWindow = window.open(url, name, 'width=' + w + ', height=' + h + ', top=' + top + ', left=' + left + options);

			// Puts focus on the newWindow
			if (window.focus) {
			    newWindow.focus();
			}

			// Add it to the stack of references
			$.popWindowReferences[name] = newWindow;

		} else { // Do not open a new window
			winObjRef.focus();
		}
	};

	/* if possible move the delegation off of $(docuemnt)! */
	$(document).on('click', '.popup-window', function(event) {
		if($(this).data('popup-prevent-default') == true) { 
			event.preventDefault();
		}
		$.popWindow($(this).data('popup-name'), $(this).data('popup-url'), $(this).data('popup-width'), $(this).data('popup-height'), $(this).data('popup-options'));
	});
});