Question

I have a global var defined in a .js file.:

If my function has an argument with the same name as the global variable, the function can not initialise the global variable:

var myvar;

function init(myvar){
    myvar= myvar;
}

But if I change the variable names so the global variable and argument have different names, the function can initialise the global variable:

var myvar2;

function init(myvar){
    myvar2= myvar;
}

(myvar2 is then initialised correctly).

Why is this the case ? javascript does not allow two variables with same name in different scope so variable shadowing is occuring ?

I thought the js engine would be be able to distinguish between method scope and global scope in the same way that java does (albeit using the this keyword)

Answer 1

That is correct; the global variable is being shadowed. Think about it. In this statement:

myvar = myvar;

if there was no shadowing, which myvar would be the global one and which the local one?