寻找一些js范围的黑客(Looking for some js scope hack)

 这里有一些你可能或可能不知道的javascript函数参数变量的有趣行为： 
 
function foo(bar) {
    console.log('bar was:', bar); 
    arguments[0] = 'zap';        
    console.log('bar now:', bar); 
}  

foo('bam'); 
// bar was: bam
// bar now: zap
 
 正如您所见， bar变量现在指向另一个值。 
 
 我想以一种稍微奇怪的方式利用这种行为，我想知道是否有可能以某种方式从函数范围外部改变参数值？ 
 
 也许使用call / apply或其他一些trycky js功能？ 
 
 所以我可以在调用后更改函数参数的值，例如： 
 
function chooseNumber(number) { 
    setInterval(function() { 
        console.log('I choosed:', number) 
    }, 1000) 
}

chooseNumber(1);
// I choosed: 1
// I choosed: 1
// I choosed: 1
// ...
 
 然后，如果我决定改变主意，我怎样才能输出初始函数： 
 
// I choosed: 2
// I choosed: 2
// I choosed: 2
// ...

Here some interesting behaviour of javascript function arguments variable that you may be or maybe not aware of:
 
function foo(bar) {
    console.log('bar was:', bar); 
    arguments[0] = 'zap';        
    console.log('bar now:', bar); 
}  

foo('bam'); 
// bar was: bam
// bar now: zap
 
As you can see bar variable now pointing out to another value. 
 
I want to make use of such behavior in a slightly strange way, I want to know is it possible to change argument value from the outside of the function scope somehow? 
 
Maybe using call/apply, or some other trycky js features?
 
So I can change the value of function argument after it was called, for example:
 
function chooseNumber(number) { 
    setInterval(function() { 
        console.log('I choosed:', number) 
    }, 1000) 
}

chooseNumber(1);
// I choosed: 1
// I choosed: 1
// I choosed: 1
// ...
 
Then if I dicided to change my mind, how can I make so that initial function would output: 
 
// I choosed: 2
// I choosed: 2
// I choosed: 2
// ...

原文：https://stackoverflow.com/questions/18290276