Is there a short way to write the following using either JavaScript or jQuery?

if (this.id==="a" || this.id==="b" || this.id==="c" || this.id==="d")

Is there a short way to write the following using either JavaScript or jQuery?

if (this.id==="a" || this.id==="b" || this.id==="c" || this.id==="d")

• javascript
• if-statement

• 5 Here's a page to pare the performance of various suggestions below: jsperf./set-memberbship – Jason LeBrun Commented Jan 31, 2011 at 2:21
• @Jason LeBrun I have a +1 for the nice demo -- but as [more-often-then-not] always, clarity first. I blame my CPU for the slow FF posting ;-) – user166390 Commented Jan 31, 2011 at 3:12

5 Answers 5

How about this?

if ( this.id in { "a":1, "b":1, "c":1, "d":1 } ) {
  ...
}

... or this?

if("abcd".indexOf(this.id) > -1) {
   ...
}

if ( ['a','b','c','d'].indexOf( this.id ) >= 0 ) { ... }

or

if ( this.id in {'a':0,'b':0,'c':0,'d':0} ) { ... }

One possibility is a switch statement.

switch(this.id){case"a":case"b":case"c":case"d":
    //do something
}

You can try the following code. Especially when you have more than four test values.

if (/^[abcdef]$/.test(this.id)) {
    ...
}

The inline anonymous hash (d in o) performance was misrepresented in the tests as originally written, because the hash wasn't inline in the test.

Oddly enough, the true inline hash case, pared to the predefined hash case, is much slower in Firefox 4, but 50% faster in Chrome 12.

But a more important point is that d in o misses the point of a hash—that you don't have to iterate to find things.

Two lines, but still pretty short, and by far the fastest:

var o = {a:1,b:1,c:1,d:1};
if(o[this.id]){...}