<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>JS的三个属性</title> <script type="text/javascript" src="tools.js"></script> </head> <body> <script type="text/javascript"> var str = "wwee123"; //1.length--字符串长度 println(str.length);//7 //2.constructor--相当于Java中的instanceof() println(str.constructor);//function String() { [native code] } println(str.constructor == String);//true //3.prototype--相当重要!!用它可以向对象添加属性和方法(所有对象都有) //添加属性 String.prototype.age = 19; println("age:"+"aa".age);//age:19 //添加方法 String.prototype.toCharArray = function(){ var res = []; for(var i = 0;i<this.length;i++){ res[i] = this.charAt(i); } return res; } println(str + " -> "+str.toCharArray());//wwee123 -> w,w,e,e,1,2,3 </script> </body> </html>
function print(e){ document.write(e); } function println(e){ document.write(e+"<br>"); }