CODEWITHSUNDEEP
javascriptrandomduplicatesnumbers
Peter Stark
Peter Stark

Reputation: 77

Picking Non-duplicate Random Numbers using JavaScript

How would I pick 5 random lottery numbers without having duplicate numbers? The code below is what I have so far and I just can't figure out where to insert the code to loop through to pick out duplicate numbers and reassign new numbers? I've tried adding if and else along with forEach function but it didn't work. This is the code I have so far. Thank you in advance.

let lotto = [];
    for(let i = 0; i < 5; i++){
      lotto[i] = Math.floor(Math.random() * 69) + 1;
    }

const sorting = lotto.sort((a,b) => a - b);
    console.log(sorting);

Upvotes: 4

Views: 722

Answers (2)

Edwin Felipe
Edwin Felipe

Reputation: 21

Considering the process will run at leats one time, the best solution is to use a do while loop and verify if this number already exist in the list.

const lotto = [];

do {
    const random = Math.floor(Math.random() * 69) + 1;
    if(!lotto.includes(random)) lotto.push(random);
} while(lotto.length < 5);

const sorting = lotto.sort((a, b) => a - b);
console.log(sorting);

Upvotes: 2

Kelvin Schoofs
Kelvin Schoofs

Reputation: 8718

Two solutions:

  1. Create a list of your numbers, then pick (and remove) 5 from them.
  2. Create a loop that keeps generating numbers until it has 5 unique ones.

Your attempt can be adapted for solution 2:

let lotto = [];
while(lotto.length < 5) {
    console.log('Got', lotto.length, 'numbers!');
    // Changed 69 to 5 to "force" clashes (well, make it very likely)
    const num = Math.floor(Math.random() * 5) + 1;
    if (!lotto.includes(num)) lotto.push(num);
}

const sorting = lotto.sort((a, b) => a - b);
console.log(sorting);

Upvotes: 3

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