What 'use strict'; isnt working with this function and variable?

Question

'use strict';
            
function NAME2 (){
  name = 'Smith';
  console.log(name);    
}
NAME2();

function NAME3 (){
  name = 'John'; 
  console.log(name);
}
NAME3();

As you can see in both the functions, I havent used any variable keyword to define the variable thats somehow still executing.

What's wrong?

Or is it simply optional to use variable keyword in JS?

`name` is built-in global variable in browsers. Use a different variable name (e.g. `xyz`). — Felix Kling, Sep 20 '20 at 18:36
No my friend it will give you an error if you just write sname instead of name for example, the reason you don't get an error with the name variable is because it's a property of the window object, so you are just reassigning it — Saadi Toumi Fouad, Sep 20 '20 at 18:37

score 2 · Answer 1 · answered Sep 20 '20 at 18:36

2

Assigning to an undeclared variable is forbidden in strict mode, but in the context of a browser, name is predeclared in the global scope.

This would error if you were to run the code outside of a browser:

answered Sep 20 '20 at 18:36

Quentin

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Thanks, so is 'name' window's property? Like 'this' is a window's method? – prettyversatile Sep 20 '20 at 18:52
`name` is a property of the `window` object and thus a global variable. `this` is not a method of `window`. – Quentin Sep 20 '20 at 18:54

What 'use strict'; isnt working with this function and variable?

1 Answers1