JavaScript中apply方法的应用技巧小结

Function.prototype.call = function () {
 var ctx = [].shift.apply(arguments)
 return this.apply(ctx, arguments)
}

Function.prototype.bind = function () {
 var ctx = [].shift.apply(arguments),
  args = [].slice.apply(arguments),
  self = this
 return function () {
  return self.apply(ctx, args.concat([].slice.apply(arguments)))
 }
}

Function.prototype.currying = function () {
 var args = [],
  self = this
 return function () {
  if (arguments.length === 0) {
   return self.apply(this, args)
  } else {
   [].push.apply(args, arguments)
   return arguments.callee
  }
 }
}
//用法
var add = function () {
 var sum = 0
 for (var i = 0; i < arguments.length; i++) {
  sum += arguments[i]
 }
 return sum
}.currying()
add(2) //并未求值
add(3, 3) //并未求值
add(4) //并未求值
console.log(add()) //12

Function.prototype.currying = function () {
 var args = [],
  self = this
 var f = function () {
  if (arguments.length === 0) {
   return self.apply(this, args)
  } else {
   [].push.apply(args, arguments)
   return f
  }
 }
 return f
}

Function.prototype.uncurrying = function () {
 var self = this
 return function () {
  var obj = [].shift.apply(arguments)
  return self.apply(obj, arguments)
 }
}
// 用法
var push = Array.prototype.push.uncurrying()
var obj = {}
push(obj, '嘿')
console.log(obj) //{0: "嘿", length: 1}

Function.prototype.uncurrying = function () {
 var self = this
 return function () {
  return Function.prototype.call.apply(self, arguments)
  //有点绕，其实就是return self.call(args[0], args[1], args[2]...)
 }
}

Array.prototype.max = function () {
 return Math.max.apply(null, this)
}
console.log([1, 3, 5, 2].max()) //5