How to reduce multiple OR conditions in if statement in JavaScript? [duplicate]

Question

I have a condition:

if (item == 'a' || item == 'b' || item == 'c' || item == 'd' || item == 'e') {
    // statements
}

How can I reduce the branching? Is there any other way to write this in JavaScript.

Can use switch. developer.mozilla.org/en/docs/Web/JavaScript/Reference/… — Swaraj Giri
– Swaraj Giri, Commented Sep 1, 2016 at 5:09

Rob M. · Accepted Answer · 2016-09-01 05:22:05Z

7

You can also use the newer Array.includes

if (['a','b','c','d','e'].includes(item)) {
  ...
}

Another option (for the very specific case you posted) would be to compare unicode point values using </>

if (item >= 'a' && item <= 'e') {
   ...
}

edited Sep 1, 2016 at 5:22

answered Sep 1, 2016 at 5:11

Rob M.

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3 Comments

tresf Over a year ago

Word of caution, Array.includes is not supported on IE11 or Edge although a polyfill can include it.

Rob M. Over a year ago

@QZSupport Array.includes is actually supported in Edge (not in IE11 though). Thanks for noting that! :)

tresf Over a year ago

thanks, updated.

Pranav C Balan · Accepted Answer · 2016-09-01 05:10:19Z

5

Use Array#indexOf method with an array.

if(['a','b','c','d','e'].indexOf(item) > -1){
   //.........statements......
}

answered Sep 1, 2016 at 5:10

Pranav C Balan

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1 Comment

Kaiido Over a year ago

It does reduce the code length but not the branching at all.

Nikhilesh K V · Accepted Answer · 2016-09-01 05:25:48Z

3

You can use an array as shown below.

var arr = ['a','b','c','d','e'];
if(arr.indexOf(item) > -1) 
{
   //statements
}

edited Sep 1, 2016 at 5:25

answered Sep 1, 2016 at 5:10

Nikhilesh K V

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Comments

Max · Accepted Answer · 2016-09-01 05:28:20Z

2

This would work nicely:

if('abcde'.indexOf(item) > -1) {
    ...
}

You could also use the newer String.prototype.includes(), supported in ES6.

if('abcde'.includes(item)) {
    ...
}

edited Sep 1, 2016 at 5:28

answered Sep 1, 2016 at 5:21

Max

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2 Comments

Pranav C Balan Over a year ago

if item is ab ?

Max Over a year ago

@PranavCBalan If it's ab, he'll use your answer. His example doesn't show ab so I would assume he doesn't require that functionality. kk :D

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