使用var或不使用var定义对象 [英] defining an object with var or without var

问题描述

var ninja = { 
  yell: function(n){ 
    return n > 0 ? ninja.yell(n-1) + "a" : "hiy"; 
  } 
}; 
console.log( ninja.yell(4) == "hiyaaaa", "A single object isn't too bad, either." ); 

var samurai = { yell: ninja.yell }; 
var ninja = null; 

try { 
  samurai.yell(4); 
} catch(e){ 
  console.log( false, "Uh, this isn't good! Where'd ninja.yell go?" ); 
}

问题是 Var ninja = null

这是另一个对象吗？

还是和我在第一行写的一样？

or it same as i wrote it in first line?

我想这是另一个新对象，因为我用var定义它？

I guess it is another new object cause i define it with var?

但是这是假的，因为out put是false并且catch body运行了。到底是什么？
我也有与上面相同的例子，但这有什么不同的原因？

but this is false because out put is false and catch body ran. what the heck is this? and i also have the same example like above but this is working differently why?

var obj={name: "faizan", age:31}
    var obj2 = obj;//obj2 pointing to the same memoray location of obj
    console.log("before making null obj::",obj2.name);
    console.log(obj==obj2,"::checking obj==obj2 while var obj2=obj");
    obj=null;  //obj became null
    console.log("after making null obj::",obj2.name);//now this will need to be null but is working why??

推荐答案

变量只能在特定范围内声明一次。第二个 var ninja = null; 忽略 var 声明，只需重新分配相同的变量，就像你要做的那样写 ninja = null; 。

A variable can only be declared once in a particular scope. The second var ninja = null; ignores the var declaration, and simply reassigns the same variable, as if you'd written ninja = null;.

JS Lint 将警告变量的重新声明。

JS Lint will warn about redeclarations of a variable.

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