Javascript Function 对象 属性和方法

arguments

function.arguments[0|1|2|...|n]

当前正在运行的函数的参数

func.arguments0,对参数0 的引用

arguments.callee

function.arguments.callee

当前在正在执行的函数引用，可用于函数的递归。 该属性仅当相关函数正在执行时才可用。

function factorial(n){  if (n <= 0)     return 1;  else     return n * arguments.callee(n - 1)}document.write(factorial(4));

caller

functionName.caller

获取调用当前函数的函数。

function CallLevel(){   if (CallLevel.caller == null)      return("CallLevel was called from the top level.");   else      return("CallLevel was called by another function.");}document.write(CallLevel());// Output: CallLevel was called from the top level.

constructor

object.constructor

指定创建一个对象的函数.

// A constructor function.function MyObj() {    this.number = 1;}var x = new String("Hi");if (x.constructor == String)    document.write("Object is a String.");document.write (" ");var y = new MyObj;if (y.constructor == MyObj)    document.write("Object constructor is MyObj.");// Output:// Object is a String.// Object constructor is MyObj.

length

functionName.length

创建函数的实例后，脚本引擎将该函数的 length 属性初始化 为该函数定义中的参数数量。

function ArgTest(a, b){    var s = "";    s += "Expected Arguments: " + ArgTest.length;    s += " ";    s += "Passed Arguments: " + arguments.length;    return s;}document.write(ArgTest(1, 2));// Output: // Expected Arguments: 2// Passed Arguments: 2

prototype

objectName.prototype

所有内部 JavaScript 对象都有一个只读的 prototype 属性。   可将属性和方法添加到原型中，但不能为 对象分配其他原型。   但是，可以向用户定义的对象分配新的原型。

function array_max( ){    var i, max = this0;    for (i = 1; i < this.length; i++)    {    if (max < thisi)    max = thisi;    }    return max;}Array.prototype.max = array_max;var myArray = new Array(7, 1, 3, 11, 25, 9);document.write(myArray.max());// Output:// 25

apply()

apply([thisObj,argArray])

调用函数，并用指定对象替换函数的 this 值， 同时用指定数组替换函数的参数。

function callMe(arg1, arg2){    var s = "";    s += "this value: " + this;    s += " ";    for (i in callMe.arguments) {        s += "arguments: " + callMe.argumentsi;        s += " ";    }    return s;}document.write("Original function: ");document.write(callMe(1, 2));document.write(" ");document.write("Function called with apply: ");document.write(callMe.apply(3, 4, 5 ));// Output: // Original function: // this value: object Window// arguments: 1// arguments: 2// Function called with apply: // this value: 3// arguments: 4// arguments: 5

call()

call([thisObj[, arg1[, arg2[,  , argN]]]])

调用一个对象的方法，用另一个对象 替换当前对象。

function callMe(arg1, arg2){    var s = "";    s += "this value: " + this;    s += " ";    for (i in callMe.arguments) {        s += "arguments: " + callMe.argumentsi;        s += " ";    }    return s;}document.write("Original function: ");document.write(callMe(1, 2));document.write(" ");document.write("Function called with call: ");document.write(callMe.call(3, 4, 5));// Output: // Original function: // this value: object Window// arguments: 1// arguments: 2// Function called with call: // this value: 3// arguments: 4// arguments: 5

bind()

function.bind(thisArg[,arg1[,arg2,argN]])   返回值 与 function 函数相同的新函数， thisArg 对象和初始参数除外

对于给定函数，创建具有与原始函数相同的 主体的绑定函数。 在绑定功能中，this 对象解析为传入的对象。 该绑定函数具有指定的初始参数。

// Define the original function.var checkNumericRange = function (value) {    if (typeof value !== 'number')        return false;    else        return value >= this.minimum && value <= this.maximum;}// The range object will become the this value in the callback function.var range = { minimum: 10, maximum: 20 };// Bind the checkNumericRange function.var boundCheckNumericRange = checkNumericRange.bind(range);// Use the new function to check whether 12 is in the numeric range.var result = boundCheckNumericRange (12);document.write(result);// Output: true // Define the original function with four parameters.var displayArgs = function (val1, val2, val3, val4) { document.write(val1 + " " + val2 + " " + val3 + " " + val4);}var emptyObject = {};// Create a new function that uses the 12 and "a" parameters// as the first and second parameters.var displayArgs2 = displayArgs.bind(emptyObject, 12, "a");// Call the new function. The "b" and "c" parameters are used// as the third and fourth parameters.displayArgs2("b", "c");// Output: 12 a b c