get always 10 numbers from randoms - Javascript

Question

I need help with my code. I want to get 10 random numbers every time it rolls and it can't have duplicated, this is my code:

for(let j = 1; j <= 21; j++) {
    const number = (Math.floor((Math.random() * j) + 1))
    const genNumber = array.indexOf(number);
    if (genNumber === -1) {
        array.push(number);
    }
}

I have no idea how I can get exactly 10 numbers every time, anyway it can be written with js or jquery it doesnt metter for me. Hope I can get help here.

Why does your `for ...` loop go until 21? Have you considered dropping it to 10? — Wyatt Arent, Apr 20 '18 at 21:49
using a while loop and continuing until the size of array is 10 — Md Johirul Islam, Apr 20 '18 at 21:50
its 21 becasue im creating a memory game and i have at the moemnt 21 pictures and it randomly add different images — Mariusz, Apr 20 '18 at 21:53
You are confusing the loop counter (21, which should be the max number to get) with the amount of numbers to generate, which should be 10. — Scott Marcus, Apr 20 '18 at 21:55

score 0 · Answer 1 · answered Apr 20 '18 at 21:56

I don't really understand what your code is intended to do, but to get exactly 10 unique random numbers I'd use a Set and loop until it's filled. I have no idea why you loop 21 times for 10 items though...

let s = new Set();
while (s.size < 10) {
  s.add((Math.floor(Math.random() * 21 /* ??? */) + 1));
}

console.log([...s]);

score 0 · Answer 2 · answered Apr 20 '18 at 21:56

0

You're almost there, but instead of using a for loop, use a while loop that continues as long as there are less than 10 things in the array:

const array = [];
const j = 21; // Pick numbers between 1 and 21 (inclusive)

while (array.length < 10) {
    const number = (Math.floor((Math.random() * j) + 1))
    const genNumber = array.indexOf(number);
    if (genNumber === -1) {
        array.push(number);
    }
}

console.log(array);

answered Apr 20 '18 at 21:56

CRice

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That works for me , im glad for your help , i forget about while loop , thanks you so much :) – Mariusz Apr 20 '18 at 21:59

get always 10 numbers from randoms - Javascript

2 Answers2