Question

When I used a new variable something.something or this.something, my code worked when I omitted the var keyword:

this.something = 1;
something.something = 1;

but when I write

var this.something = 1;
var something.something = 1;

it doesn’t work.

Why?

Answer 1

I suppose because var expects a valid identifier, and . is not a valid character for an identifier.

It thinks you want the variable name to actually be this.something, which isn’t valid.

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When testing the two versions, I get slightly different errors.

The one with this.something tells me:

SyntaxError: Unexpected token this

The one with something.something tells me:

SyntaxError: Unexpected token .

Same error, but the invalid token in the first is the keyword this.