Question

I want to generate atleast 1000 unique random numbers with 10 digit using
javascript in a loop. Is this possible? Or is Javascript a wrong thing to do this?

UPDATE: How will you be sure that duplicates are not created?

Answer 1

Here’s how I would do it:

var arr = [],
    track = [],
    min = 1000000000,
    max = 9999999999,
    qty = 1000,
    ii = 0,
    rnd;

while (ii < qty) {
    rnd = Math.floor(Math.random() * (max - min + 1)) + min;
    if (!track[rnd]) {
        arr[ii] = track[rnd] = rnd;
        ii += 1;
    }
}

Here’s a working example: http://jsfiddle.net/mTmEs/

Now, if something went awry with Math.random and for some reason it were to generate a lot of duplicates, this code could take a long time to complete. I don’t think there is any way around this kind of potential problem though when you’re talking about large quantities of unique random numbers.