How to check whether an array contains an element

Question

I'd like to restrict keys that can be pressed.

$('.txtComments').keydown(function (event) {
  var keys = new Array();
  keys[0] = "8";
  keys[1] = "46";
  keys[2] = "37"
  keys[3] = "39"

  if(!(....)) //Check whether the keyCode is either of 8, 46, 37, or 39. 
  {
     event.preventDefault();  
  }
});

Thanks for helping

`var keys = [8,46,37,39];`, then you can use `$.inArray` and `event.which` — Kevin B, Mar 05 '13 at 19:06
Try using [`$.inArray`](http://api.jquery.com/jQuery.inArray/) — gen_Eric, Mar 05 '13 at 19:07
Use `let excludeCode = [20, 16, 17, 18, 32]` `if ( excludeCode.includes(event.which) ) {}` — Vito Bryliano, Jun 23 '22 at 09:29

score 3 · Answer 1 · answered Mar 05 '13 at 19:07

3

The simplest (and fastest) here would be to use an object as map :

   var keys = {};
   keys[8] = true;
   ...

   if (!keys[event.which]) {
     ...

Note that I suggest to use event.which instead of the keycode for better compatibility.

answered Mar 05 '13 at 19:07

Denys Séguret

372,613
87
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Alnitak · Accepted Answer · 2013-03-05T20:41:51.740

There are so many ways to implement this:

Just hard code it:

var keyCode = event.which;

if (keyCode != 8 && keyCode != 46 ...)

or check an array:

var keys = [8, 46, ...];
if (keys.indexOf(keyCode) < 0)

or the jQuery equivalent:

if ($.inArray(keyCode, keys) < 0)

or check an object:

var keys = { 8: 1, 46: 1, ... }
if (! (keyCode in keys) )  // or if (!keys[keyCode])

or a switch:

switch (keyCode) {
    case 8: case 46: ...
        // do nothing
        break;
    default:
        event.preventDefault();
}

score 1 · Answer 3 · answered Mar 05 '13 at 19:07

1

jQuery provides the utility method jQuery.inArray() to check if an array contains a value.

answered Mar 05 '13 at 19:07

Ruben Infante

3,125
1
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score 0 · Answer 4 · answered Mar 05 '13 at 19:07

if(!keys.in_array(event.keyCode));

And change your keydown to keypress

<script type="text/javascript">
// Benoit Asselin - http://www.ab-d.fr
Array.prototype.in_array = function(p_val) {
    for(var i = 0, l = this.length; i < l; i++) {
        if(this[i] == p_val) {
            return true;
        }
    }
    return false;
}
</script>

QuentinUK · Answer 5 · 2013-03-05T19:28:15.707

0

You can use:-

   var keys = [];
    keys[8] = keys[4] = keys[37] = keys[39] = true;

if(keys[keyval]){

}

edited Mar 05 '13 at 19:28

answered Mar 05 '13 at 19:17

QuentinUK

2,997
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How to check whether an array contains an element

5 Answers5