for ... in 语句==类似于java的for each== for(var 变量in 对象){ } for(var n in obj){ console.log("属性名:"+n); console.log(“属性值:”+obj[n]); } 关于取值的地方和java还是不一样的7.函数中的方法 (P79)call()和apply() 都是函数对象的方法,需要通过函数对象来调用 当对函数调用...
诸如toString和valueOf等方法实际上都保存在Object.prototype名下(原生构造函数比如Function,Array等 在自己原型上重写了toString)。在ECMAScript5中,prototype属性是不可枚举的,因此使用for–in无法发现。 Object.getOwnPropertyDescriptor(Function,’prototype’);// Object {writable: false, enumerable: false, configura...
诸如toString和valueOf等方法实际上都保存在Object.prototype名下(原生构造函数比如Function,Array等在自己原型上重写了toString)。在ECMAScript5中,prototype属性是不可枚举的,因此使用for-in无法发现。Object.getOwnPropertyDescriptor(Function,'prototype');//Object {writable: false, enumerable: false, configurable: f...
Thebind()method solves this problem. In the following example, thebind()method is used to bind person.display to person. This example will display the person name after 3 seconds: Example constperson = { firstName:"John", lastName:"Doe", ...
We didn't attach themultiply()function as a method to the window object yet we can invoke it as one! Objects and global objects in functions Speaking of objects and global objects, thethis keywordattains the value of an object when used inside a function and owns that function. When we ...
Theapply()method is similar to thecall()method (previous chapter). In this example thefullNamemethod ofpersonisappliedonperson1: Example constperson = { fullName:function() { returnthis.firstName+" "+this.lastName; } } constperson1 = { ...
The following will be output to theweb browser console log: 2 In this example, the min() method returned 2 which is the smallest value from the array calledtotn_array. This array consisted of 5 elements with the numeric values: 2, 4, 6, 8 and 10....
所谓函数重载(method overloading)即函数名称一样,但输入输出不一样。也就是说允许函数有各种不同的输入,根据不同的输入,返回的结果不同。jQuery之父John Resig提出了一个非常巧(bian)妙(tai)的方法,利用了闭包。 假设有如下一个需求,有一个people对象,里面存着一些人名,如下: ...
export function 中的method export 函数 export:1.导出定义的变量2.直接在export定义导出的函数或变量3.导出函数或变量重命名(as)4.export default(不需要变量名称)js文件只有一个功能5.export {fn as default}6.export * from ..import1.import add from math2.import * from math3.import * as e json ...
JavaScript进阶系列之function篇 每天都在codeing,但是如果没有总结的话,根本记不住。以后定期写文章,不管有没有人看都会有一定的收获。 目录: 函数的参...