js closure and prototype
js闭包 和 prototype
function test(){
var p=200;
function q(){
return p++;
}
return q;
}
var s = test();
alert(s());
alert(s());闭包： 在外部访问函数内部的变量：通过函数内部的函数，return 出 函数内部的变量
原型链继承：
<script type="text/javascript">
//定义一个people类，包括eye和hand两个属性，和 run 的方法。
function people(ec,hc){
this.eye = ec;
this.hand = hc;
}
people.prototype.run = function(){
console.log("人类用" + this.hand + "的腿跑步");
}
//定义chin类，调用people 的 call 方法，继承people的 eye 和 hand 属性。
function chin(ec,hc){
people.call(this,ec,hc);
}
//创造people类的原型副本（此时该原型副本的构造方法是指向people的，所以需要修正该构造方法，改成chin）
var _prototype = Object.create(people.prototype);
_prototype.constructor = chin;
//把chin的原型赋值给 _prototype 。此时 chin 即继承了people的 run方法。但是没有改变people的原型。
chin.prototype = _prototype;
//给chin类增加一个 sw方法。
chin.prototype.sw = function(){
console.log("中国人游泳很厉害");
}
var s = new chin("黑眼睛","黄皮肤");
console.log(s);
console.log(s.eye);
console.log(s.run());
console.log(s.sw());
var p = new people("蓝眼睛","黑皮肤");
console.log(p);
</script>结果如下：
call：
function a(data){
alert(this.q + data);
}
var s = {
q:100
}
//call的第一个参数是 this，当传入 s 时，即把this 改成了 s ，可以访问 s 内部的变量q 。
a.call(s, 1);结果 alert 101
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