Function ctx

lib/web/polyfill.js:125–141

(fn, that, length)

}
// Optional / simple context binding
function ctx(fn, that, length){
  assertFunction(fn);
  if(~length && that === undefined)return fn;
  switch(length){
    case 1: return function(a){
      return fn.call(that, a);
    };
    case 2: return function(a, b){
      return fn.call(that, a, b);
    };
    case 3: return function(a, b, c){
      return fn.call(that, a, b, c);
    }
  } return function(/* ...args */){
      return fn.apply(that, arguments);
  }
}
// Fast apply
// http://jsperf.lnkit.com/fast-apply/5
function invoke(fn, args, that){