paulirish

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.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

samgiles

// [B](f: (A) ⇒ [B]): [B]  ; Although the types in the arrays aren't strict (:
Array.prototype.flatMap = function(lambda) { 
    return Array.prototype.concat.apply([], this.map(lambda)); 
};

james2doyle

// easing functions http://goo.gl/5HLl8
Math.easeInOutQuad = function (t, b, c, d) {
  t /= d/2;
  if (t < 1) {
    return c/2*t*t + b
  }
  t--;
  return -c/2 * (t*(t-2) - 1) + b;
};