Question

I found three ways to cast a variable to String in JavaScript.
I searched for those three options in the jQuery source code, and they are all in use.
I would like to know if there are any differences between them:

value.toString()
String(value)
value + ""

DEMO

They all produce the same output, but does one of them better than the others?
I would say the + "" has an advantage that it saves some characters, but that’s not that big advantage, anything else?

Answer 1

They do behave differently when the value is null.

• null.toString() throws an error – Cannot call method ‘toString’ of null
• String(null) returns – “null”
• null + "" also returns – “null”

Very similar behaviour happens if value is undefined (see jbabey’s answer).

Other than that, there is a negligible performance difference, which, unless you’re using them in huge loops, isn’t worth worrying about.