Question

Em. I’m looking at the easing equation here:

var easing = function( t, b, c, d ) {
   return c * ( t /= d ) * t * t * t + b;
}

So presumably one can write it like this:

var easing = function( t, b, c, d ) {
   return c * ( t = (t/d) ) * t * t * t + b;
}

or like this ? mmm.. not sure about this one:

var easing = function( t, b, c, d ) {
   return c * t = c * (t/d) * t * t * t + b;
}

How exactly is this equation being parsed by javascript, I mean, we get:

return number = number;

wtf? How is this being handled.

Answer 1

Assuming that expression are evaluated from left to right, the expression can be simplified by following steps:

1)

var easing = function( t, b, c, d ) {
   return c * ( t = (t/d) ) * t * t * t + b;
}

2)

var easing = function( t, b, c, d ) {
   t = t/d;
   return c * t * t * t * t + b;
}

3)

var easing = function( t, b, c, d ) {
   return c * Math.pow(t/d, 4) + b;
}

JsFiddle for the code: http://jsfiddle.net/caGWz/