javascript - JavaScript 的简单继承

Question

function StringStream() {}
StringStream.prototype = new Array();
StringStream.prototype.toString = function(){ return this.join(''); };

调用new StringStream(1,2,3)给出一个空数组

x = new StringStream(1,2,3)

给出

StringStream[0]
__proto__: Array[0]

有人可以解释一下为什么没有调用父类(super class)(Array)构造函数吗？

Answer 1

仅仅因为 StringStream.prototype 是一个数组，StringStream 构造函数也不会被 Array 替换。

您应该自己实现:http://jsfiddle.net/gBrtf/ .

function StringStream() {
    // push arguments as elements to this instance
    Array.prototype.push.apply(this, arguments);
}

StringStream.prototype = new Array;

StringStream.prototype.toString = function(){
    return this.join('');
};