Javascript简易教程 1

关于This
1. 它是一个关键字，并不是变量名或属性名。
2. 它实际指function所关联的对象，如果function没有关联任何对象，则this是Global对象
var msg = 'I am global';
function showMsg(){
alert(this.msg);
};
function nestedShowMsg (){
var nested = function(){
alert(this.msg);
};
nested(); 
};
var owner = {msg:'I am local'};
owner.showMsg = showMsg;
owner.nestedShowMsg = nestedShowMsg;
showMsg();  //should be 'I am global'
owner.showMsg(); //should be 'I am local'
owner.nestedShowMsg();should be 'I am global'