Shorten JS if or statement [duplicate]

Answer 1

If your cases are not that simple to be expressed by this:

if (1 <= x && x <= 4)

You could use an array and indexOf:

if ([1,2,3,4].indexOf(x) > -1)

Note that indexOf might need to be re-implemented.

Answer 2

How about:

if (x > 0 && x < 5) {
} 

Answer 3

You can use use Array.indexOf

[1,2,3,4].indexOf(x) !== -1

You can also use objects as some kind of hash map:

//Note: Keys will be coerced to strings so
// don't use this method if you are looking for an object or if you need
// to distinguish the number 1 from the string "1"
my_values = {1:true, 2:true, 3:true, 'foo':true}
my_values.hasOwnProperty('foo')

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By the way, in most cases you should usi the "===" strict equality operator instead of the == operator. Comparison using "==" may do lots of complicated type coercion and you can get surprising results sometimes.

Answer 4

You could write a function:

function isAny(x) {
  for (var i = 1; i < arguments.length; ++i)
    if (arguments[i] === x) return true;
  return false;
}

Then you can say:

if (isAny(x, 1, 2, 3, 4)) { /* ... */ }

(Whether to use "===" or "==" would depend on the exact semantics you want.)

Answer 5

Not without writing a function that takes an array as an input and returns true/false, or some sort of array search. It would be hard to maintain/other devs to read. And it would be significantly slower. So just stick with the semantically correct longer version.

Also a good way to see if anything can be shortened significantly is to run it through the close compiler and see what it comes out with.