Question

I have a variable that can either be boolean false, or an integer (including 0). I want to put it in a switch statement like:

switch(my_var){
    case 0:
         // Do something
         break;
    case 1:
         // Do something else
         break;
    case false:
         // Some other code
}

In my tests in Google Chrome, it seems to work perfectly, but I’m a little nervous to use it because I’m afraid that in some browsers, if my_var is false, it might execute the first case since 0 == false.

I’m just wondering if there is anything official in JavaScript that says the switch statement will use strict comparison such that 0 !== false, but I can’t find anything myself, and I’m not sure if this will work well in different JavaScript engines. Does anybody know if the comparison done by a switch statement is guaranteed to be strict?

Answer 1

Take a look at ECMA 262, section 12.11, the second algorithm, 4.c.

c. If input is equal to clauseSelector as defined by the === operator, then…