function Support() { this.rangeBounds = this.testRangeBounds(); this.cors = this.testCORS(); } Support.prototype.testRangeBounds = function() { var range, testElement, rangeBounds, rangeHeight, support = false; if (document.createRange) { range = document.createRange(); if (range.getBoundingClientRect) { testElement = document.createElement('boundtest'); testElement.style.height = "123px"; testElement.style.display = "block"; document.body.appendChild(testElement); range.selectNode(testElement); rangeBounds = range.getBoundingClientRect(); rangeHeight = rangeBounds.height; if (rangeHeight === 123) { support = true; } document.body.removeChild(testElement); } } return support; }; Support.prototype.testCORS = function() { return typeof((new Image()).crossOrigin) !== "undefined"; };