prototype 属性 (Number)

为number的类返回原型的引用。

语法

number.prototype

备注

number参数是数字的名称。

Use the prototype property to provide a base set of functionality to a class of objects. New instances of an object "inherit" the behavior of the prototype assigned to that object.

For example, to add a method to the Number object that returns the number of (integer) digits, declare the function, add it to Number.prototype, and then use it.

function number_digits() {
  var digits = 0;
  var num = this;
  while (num) >= 1) {
    digits++;
    num /= 10;
  }
  return digits;
}
Number.prototype.digits = number_digits;
var myNumber = new Number(3456.789);
document.write(myNumber.digits());
// Output:
// 4

All intrinsic JavaScript objects have a prototype property that is read-only. Properties and methods may be added to the prototype, but the object may not be assigned a different prototype. However, user-defined objects may be assigned a new prototype.

The method and property lists for each intrinsic object in this language reference indicate which ones are part of the object's prototype, and which are not.

必备条件

在以下文档模式中受支持：怪异模式、Internet Explorer 6标准模式、Internet Explorer 7标准模式、Internet Explorer 8标准模式、Internet Explorer 9标准模式、Internet Explorer 10标准模式、Internet Explorer 11标准模式。应用商店应用（Windows 8和Windows Phone 8.1）中也受支持。请参阅版本信息。