Is it safe to assume strict comparison in a JavaScript switch statement?
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开发者_运维百科?
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...
http://qfox.nl/notes/110 answers your question. (This guy knows a lot about the nitty gritty of JavaScript)
Switches in Javascript use strict type checking (===). So you never have to worry about coercion, which prevents a few wtfjs :). If on the other hand you were counting on coercion, tough luck because you can't force it.
Yes, switch
"[uses] the strict comparison, ===
".
Source: switch - JavaScript | MDN
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