functionsbuildfunctions.js

function add(x) {return function(y) {return x + y;}}
var add5 = add(5)
add5(1)
//log, warn,info,notice


function counter() {var count = 0; return function() {count ++; return count;}}
var increment = counter()
increment() //1
increment() //2
//ajax

function partial(fn /*, args...*/) {
  // A reference to the Array#slice method.
  var slice = Array.prototype.slice;
  // Convert arguments object to an array, removing the first argument.
  var args = slice.call(arguments, 1);

  return function() {
    // Invoke the originally-specified function, passing in all originally-
    // specified arguments, followed by any just-specified arguments.
    return fn.apply(this, args.concat(slice.call(arguments, 0)));
  };
}
function addAllTheThings() {
  var sum = 0;
  for (var i = 0; i < arguments.length; i++) {
    sum += arguments[i];
  }
  return sum;
}
var addFromSix = partial(addAllTheThings, 1,2,3);
addFromSix(4) //10