Javascript：参数是变量还是常量？

Question

Let me show you a very simple example:

function abc(x, y, z){
 x = x.toLowerCase();
 return x;
}

Can I change the value of arguments of a function?

Answer 1

The arguments are variables

 function foo(x){ x = x.toLowerCase(); return x; } console.log(foo("ABC")) 

If they were constants... you wouldn't be able to set its value in the first place rendering the parameters useless

Answer 2

Yes you can, here is how to.

 function abc(x, y, z){ x = x.toLowerCase(); return x; } abc = function(x = 'totally new way') { return x; } alert(abc()); 

Answer 3

Try This:

 function abc(x, y, z) { return x.toLowerCase() } console.log( abc('HeLLo') );