Generating Unique Random Numbers with JavaScript

Question

Generating Unique Random Numbers with JavaScript

Is there a way to generate 5 unique random lottery numbers using JavaScript? I've been working on the code below, but can't seem to figure out how to ensure there are no duplicate numbers in the final selection. I tried adding conditionals and loops like forEach, but it didn't solve the issue. Could you help me with this problem? Here's the current code I'm working with. Thank you.

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);

javascript random duplicates numbers

Answer 1

Answer №1

Here are two possible solutions:

Make a list of your numbers and then select 5 by removing them one by one.
Create a loop that continues to generate numbers until it has 5 unique ones.

Your attempt can be modified for the second solution:

let lotteryNumbers = [];
while(lotteryNumbers.length < 5) {
    console.log('Got', lotteryNumbers.length, 'numbers!');
    // Changed 69 to 5 to increase chances of duplicates
    const number = Math.floor(Math.random() * 5) + 1;
    if (!lotteryNumbers.includes(number)) lotteryNumbers.push(number);
}

const sortedNumbers = lotteryNumbers.sort((a, b) => a - b);
console.log(sortedNumbers);

Answer 2

Here are two possible solutions:

Make a list of your numbers and then select 5 by removing them one by one.
Create a loop that continues to generate numbers until it has 5 unique ones.

Your attempt can be modified for the second solution:

let lotteryNumbers = [];
while(lotteryNumbers.length < 5) {
    console.log('Got', lotteryNumbers.length, 'numbers!');
    // Changed 69 to 5 to increase chances of duplicates
    const number = Math.floor(Math.random() * 5) + 1;
    if (!lotteryNumbers.includes(number)) lotteryNumbers.push(number);
}

const sortedNumbers = lotteryNumbers.sort((a, b) => a - b);
console.log(sortedNumbers);

Answer 3

Answer №2

To ensure the process runs at least once, it is recommended to utilize a do-while loop and check if the number already exists in the list.

const lotteryNumbers = [];

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

const sortedNumbers = lotteryNumbers.sort((a, b) => a - b);
console.log(sortedNumbers);

Answer 4

To ensure the process runs at least once, it is recommended to utilize a do-while loop and check if the number already exists in the list.

const lotteryNumbers = [];

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

const sortedNumbers = lotteryNumbers.sort((a, b) => a - b);
console.log(sortedNumbers);

Generating Unique Random Numbers with JavaScript

Answer №1

Answer №2

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