quan17

JavaScript Classes - ES5 vs ES6

An example that shows the difference between creating a JavaScript class and subclass in ES5 and ES6.

Reference

quan17

function mySlowFunction(baseNumber) {
	console.time('mySlowFunction');
	var result = 0;	
	for (var i = Math.pow(baseNumber, 10); i >= 0; i--) {		
		result += Math.atan(i) * Math.tan(i);
	};
	console.timeEnd('mySlowFunction');
	return result;
}

quan17

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Element

Box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
• elem.clientLeft, elem.clientTop, elem.clientWidth, elem.clientHeight
• elem.getClientRects(), elem.getBoundingClientRect()