Multiple Comparison / Assignment Operators on the Same Line in JavaScript

Question

function test(input){
   var value = input != 1;
}

In the above, what is the line inside of the function doing and how does it work?

Answer 1

First it's doing the comparison input != 1 , and then assigning the result of that (which will be true or false ) the variable value . The != is a comparison , the = is an assignment .

This is exactly the same as any other assignment: The right-hand side is evaluated, and assigned to the left-hand side.

Answer 2

See Operator Precedence .

!= has a precedence of 9 and = has a precedence of 17.

Therefore it evaluates input != 1 and then assigns the result to value .