Wait for desired environment (mobile or desktop)

environment.js

var Environment = (function () {

	var _mqDesktop, _mqMobile;

	function getMobileMediaQuery() {
		return _mqMobile || (_mqMobile = window.matchMedia("(max-width: 719px)"));
	}

	function getDesktopMediaQuery() {
		return _mqDesktop || (_mqDesktop = window.matchMedia("(min-width: 720px)"));
	}

	function isMobile() {
		return !!(window.matchMedia && getMobileMediaQuery().matches);
	}

	function isDesktop() {
		return !!(window.matchMedia && getDesktopMediaQuery().matches);
	}

	function once(mq, callback) {
		function handler() {
			mq.removeListener(handler);
			callback();
		}
		mq.addListener(handler);
	}

	function getStyle(el, cssProperty) {
		return (getComputedStyle !== "undefined") ?
			getComputedStyle(el)[cssProperty] : el.currentStyle[cssProperty];
	}

	function waitUntil(value, cb) {
		var body, detector = document.querySelector(".style-detector");
		if (!detector) {
			detector = document.createElement("div");
			detector.className = "style-detector";
			body = document.getElementsByTagName("body")[0];
			body.insertBefore(detector, body.firstChild);
		}

		var i = 100;
		(function loop() {
			var v = getStyle(detector, "zIndex");
			if (v != value) {
				i = i - 1;
				if (i >= 0) {
					setTimeout(loop, 250);
				} else {
					cb();
				}
			} else {
				cb();
			}
		}());
	}

	function waitForEnvironment(condition, mq, callback, sure, zIndex) {
		var handler = function () {
			if (sure) {
				waitUntil(zIndex, callback);
			} else {
				callback();
			}
		};
		if (condition()) {
			handler();
		} else {
			once(mq(), handler);
		}
	}

	return {
		isMobile: isMobile,
		isDesktop: isDesktop,
		waitForMobile: function (callback, sure) {
			waitForEnvironment(isMobile, getMobileMediaQuery, callback, sure, 1);
		},
		waitForDesktop: function (callback, sure) {
			waitForEnvironment(isDesktop, getDesktopMediaQuery, callback, sure, 2);
		}
	};

}());