Javascript中的继承：为什么这段代码什么都不做？

Question

What is the problem with that code?

var t={a:1};
var g={b:2};
g.prototype=new t();
alert(g.a); //do nothing

Answer 1

The variable t contains an object, not a function, so you can't use it like an object constructor.

You can use the object as prototype, but you need a constructor to make use of the prototype:

var t = { a: 1 };
function g() {
  this.b = 2;
}
g.prototype = t;
alert(new g().a);

Demo: http://jsfiddle.net/Guffa/WeuPG/

Answer 2

You use new and constructors to create Objects, but what you have as t and g now are Objects already.

This should work;

function t(){
  this.a = 1;
}

function g(){
  this.b = 2;
}

g.prototype = new t();

alert(new g().a); // 1

Answer 3

Constructor must be a function.

This is a very good article on inheritance