Javascript - check array for value

Question

I have a simple array with bank holidays:

var bank_holidays = ['06/04/2012','09/04/2012','07/05/2012','04/06/2012','05/06/2012','27/08/2012','25/12/2012','26/12/2012','01/01/2013','29/03/2013','01/04/2013','06/05/2013','27/05/2013'];

I want to do a simple check to see if certain dates exist as part of that array, I have tried:

if('06/04/2012' in bank_holidays) { alert('LOL'); }
if(bank_holidays['06/04/2012'] !== undefined) { alert 'LOL'; }

And a few other solutions with no joy, I have also tried replacing all of the forwarded slashes with a simple 'x' in case that was causing issues.

Any recommendations would be much appreciated, thank you!

(edit) Here's a jsFiddle - http://jsfiddle.net/ENFWe/

Florian Margaine · Accepted Answer · 2018-08-25T06:21:12.410

76

If you don't care about legacy browsers:

if ( bank_holidays.indexOf( '06/04/2012' ) > -1 )

if you do care about legacy browsers, there is a shim available on MDN. Otherwise, jQuery provides an equivalent function:

if ( $.inArray( '06/04/2012', bank_holidays ) > -1 )

edited Aug 25 '18 at 06:21

answered Jun 13 '12 at 13:07

Florian Margaine

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Should be the other way around: `arr.indexOf( value )` – Šime Vidas Jun 13 '12 at 13:08
Oops, I never remember that ;o) – Florian Margaine Jun 13 '12 at 13:09
@AlanKuras the jQuery version will. Or it will if you add the shim on MDN. – Florian Margaine Jun 13 '12 at 13:10
Exclusively developing for IE8 here unfortunately, and we are using jQuery - so will try the legacy browser option now! :) – Nick Jun 13 '12 at 13:10
Yep jquery is the solution, didnt saw that earlier – Alan Jun 13 '12 at 13:11
2

@Nick, you have my sympathy ... – Gabriele Petrioli Jun 13 '12 at 13:12
Hm, no joy unfortunately... it still won't display the 'lol' - I wonder if the slashes are causing the problem? Will try replacing with xs – Nick Jun 13 '12 at 13:12
1

@Nick, it should work ... http://jsfiddle.net/gaby/ycDkj/ – Gabriele Petrioli Jun 13 '12 at 13:15

ioseb · Answer 2 · 2012-06-13T13:15:26.570

7

Try this:

// this will fix old browsers
if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(value) {
    for (var i = 0; i < this.length; i++) {
      if (this[i] === value) {
        return i;
      }
    }

    return -1;
  }
}

// example
if ([1, 2, 3].indexOf(2) != -1) {
  // yay!
}

edited Jun 13 '12 at 13:15

answered Jun 13 '12 at 13:09

ioseb

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score 2 · Answer 3 · answered Jun 13 '12 at 13:10

2

This should do it:

for (var i = 0; i < bank_holidays.length; i++) {
    if (bank_holidays[i] === '06/04/2012') {
        alert('LOL');
    }
}

jsFiddle

answered Jun 13 '12 at 13:10

Barry Kaye

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Checking the complete array is not efficient in terms of computational complexity – dimib May 05 '19 at 19:32
Absolute rubbish and a ridiculous micro optimisation suggestion - as the OP states it's a simple array and if there is a match the OP can always break thus not checking the complete array. – Barry Kaye May 06 '19 at 20:08

Javascript - check array for value

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