What does += mean in javascript?

Question

I've been looking online for this answer, and it's so simple so I'm embaressed for asking, but what exactly does the "+=" do in javascript. I don't know why but I can't seem to find this on google. Please help.

Answer 1

It is syntactic sugar that allows you to add something to a variable and store the result in that variable, that is

x += 2;

is equivalent to

x = x + 2;

Answer 2

Suppose

var i = 5;

You can add 6 to i by writing

i = i + 6;

Or the equivalent short-hand way:

i += 6;

Answer 3

a += b; is a short form of a = a + b;