How to properly create JQuery inArray if statement?

Question

I am generating a list of random numbers. Each random number is added to an array, but I want to check that the same number isnt entered twice. I am having a lot of trouble trying to get the if statement to work with this and am not sure what I have done wrong.

I have created:

//INITIALISE VARS, ARRAYS
var uniquearr = [];
i = 0;

while (i < 30){

    var min = 0;
    var max = 29;
    var random = Math.floor(Math.random() * (max - min + 1)) + min;

    //SEARCH UNIQUE ARRAY FOR EXISTING
    if (jQuery.inArray(random, uniquearr) > -1){

        //ADD NUMBER TO UNIQUE ARRAY
        uniquearr.push(random);

        //*DO SOMETHING*

    } //END IF

    i++;

} //END WHILE

But the if statement never triggers. Can anyone point me in the right direction?

Maybe you should check if (jQuery.inArray(random, uniquearr) < 0) { } — Givi
– Givi, Commented Jul 8, 2013 at 6:43
he should also use correct code indenting, which should have made the error on the END IF line and END WHILE lines obvious. — Alnitak
– Alnitak, Commented Jul 8, 2013 at 6:46
Your condition is reversed, it will only add random if it already exists in the array. — Ja͢ck
– Ja͢ck, Commented Jul 8, 2013 at 6:47

Arun P Johny · Accepted Answer · 2013-07-08 06:53:31Z

3

You need to test whether the random number does not exist in the array; only then should it be added to the array.

Also another problem with the logic was, you were not adding the 30 unique numbers always as the i variable was incremented outside the if condition. Here you do not have to use a different loop variable since you can check whether the destination array is of desired size

//INITIALISE VARS, ARRAYS
var uniquearr = [], min = 0, max = 29;

//SEARCH UNIQUE ARRAY FOR EXISTING
while (uniquearr.length < 30){
    var random = Math.floor(Math.random() * (max - min + 1)) + min;
    if (jQuery.inArray(random, uniquearr) == -1){
        uniquearr.push(random);
    }//END IF

}//END WHILE

console.log('uniquearr', uniquearr)

edited Jul 8, 2013 at 6:53

answered Jul 8, 2013 at 6:42

Arun P Johny

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Comments

Ram · Accepted Answer · 2013-07-08 07:00:11Z

2

That's because your if statement always is false, your array is empty and as result $.inArray always returns -1, you should check whether the returned value is -1 or not.

while (uniquearr.length < 30) { // uniquearr.length !== 30
    var min = 0,
        max = 29,
        random = Math.floor(Math.random() * (max - min + 1)) + min;
    //SEARCH UNIQUE ARRAY FOR EXISTENCE
    if (jQuery.inArray(random, uniquearr) === -1) {
        //ADD NUMBER TO UNIQUE ARRAY
        uniquearr.push(random);
    } 
}

http://jsfiddle.net/zzL7v/

edited Jul 8, 2013 at 7:00

answered Jul 8, 2013 at 6:44

Ram

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2 Comments

Alnitak Over a year ago

best code answer, but now please actually tell the OP what he did wrong, too.

Givi Over a year ago

if you check array length remove i++;, and also remove ; at the end of the while and if blocks...

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