JavaScript Function Extensions

functions.js

// Partially apply arguments to a function. Useful for binding
// specific data to an event handler.
// Example:
//
//   var add = function (x,y) { return x + y }
//   var add5 = add.papp(5)
//   add5(7) //=> 12
//
Function.prototype.papp = function () {
  var slice = Array.prototype.slice
  var fn = this
  var args = slice.call(arguments)
  return function () {
    return fn.apply(this, args.concat(slice.call(arguments)))
  }
}

// Prevents the default action. Useful for preventing
// anchor click page jumps and form submits.
// Example:
//
//   var x = 0
//   var increment = function () { x += 1 }
//   myAnchorEl.addEventListener('click', increment.chill())
//
Function.prototype.chill = function() {
  var fn = this
  return function(e) {
    e.preventDefault()
    return fn()
  }
}

// Both prevent default and partially apply in one go.
// Example:
//
//   var x = 0
//   var increment = function (amount) { x += amount }
//   myAnchorEl.addEventListener('click', increment.coldPapp(17))
//
Function.prototype.coldPapp = function() {
  var slice = Array.prototype.slice
  var fn = this
  var args = slice.call(arguments)
  return function(e) {
    e.preventDefault()
    return fn.apply(this, args.concat(slice.call(arguments, 1)))
  }
}


Function.prototype.throttle = function (fn, waittime, threshhold, scope) {
  threshhold || (threshhold = 250);
  var last, deferTimer

  var go = function () {
    var context = scope || this

    var now = +new Date,
        args = arguments

    if (last && now < last + threshhold) {
      // hold on to it
      clearTimeout(deferTimer)

      deferTimer = setTimeout(function () {
        last = now
        fn.apply(context, args)
      }, threshhold)

    } else {
      last = now
      fn.apply(context, args)
    }
  }

  var goTimeout = null
  return function () {
    clearTimeout(goTimeout)
    goTimeout = setTimeout(go, waittime)
  }
}

Very useful functions, but check your maths: 5 +7 = 12!! in the description of papp add5(7) //=> 11