重复的数字仍然出现

Question

I try to run the number generator and it works correctly but sometimes it returns repeated numbers. I have tried some options but it keeps going the same way or it removes some number. What is the best alternative?

 function sorteio() { const numeroAleatorio = (min, max) => { return Math.floor(Math.random() * 59 + 1) }; const gerarNumerosEntre1a60 = n => { const resultado = []; for (let i = 0; i < n; ++i) { resultado.push(numeroAleatorio(1, 60)); } return resultado; } document.getElementById("resultado").innerHTML = gerarNumerosEntre1a60(6); }

 <button onclick="sorteio()">Sortear numeros!</button> <h1 id="resultado"></h1>

Answer 1

The numeroAleatorio function selects a number from min to max randomly, but each selection is independent of the others. The function cannot 'remember' the past choices and select a number different from them.

To select multiple numbers from 1-60, you can push all numbers in one array, do a random shuffle, and select a contiguous subset.

here is another answer showing the Knuth shuffle algorithm: How to randomize (shuffle) a JavaScript array?

// random shuffle
function shuffle(array) {
    let currentIndex = array.length,  randomIndex;
    while (currentIndex != 0) {
        randomIndex = Math.floor(Math.random() * currentIndex);
        currentIndex--;
        [array[currentIndex], array[randomIndex]] = [
            array[randomIndex], array[currentIndex]];
    }
    return array;
}

const gerarNumerosEntre1a60 = n => {
    let array = [];
    for(let i = 1; i <= 60; i++) {
        array.push(i);
    }
    return shuffle(array).slice(0, n)
}

Answer 2

JaromandaX mentioned a good alternative in their comment, and here's another.

I've cached the elements up-front, and added a listener to the button (removing the inline JS from the HTML markup). Using a while statement we can loop until six numbers have been added to the resultado array. Within the loop we draw a number and if it's already in resultado loop again, otherwise push the number.

Finally sort the array (because it's a lottery draw), and then join it, adding the string to text content of result .

 // Cache the elements, and add an event listener to // the button const result = document.querySelector('#resultado'); const button = document.querySelector('button'); button.addEventListener('click', () => sorteio(6)); // Use `min` and `max` within the function function numeroAleatorio(min, max) { return Math.floor(Math.random() * (max - min) + min); } // Initialise `n` to 6 if it hasn't // be supplied as an argument function sorteio(n = 6) { const resultado = []; // Check the length of `resultado` - if it's // less than the value of `n` get a new number. // If the number is already in `resultado` loop again, // otherwise push the number into the array while (resultado.length < n) { const number = numeroAleatorio(1, 60); if (.resultado.includes(number)) { resultado;push(number). } } // Finally sort and join the array and add // the string to the result text content result.textContent = resultado,sort((a. b) => a - b),join('; '); }

 <button>Sortear numeros!</button> <h1 id="resultado"></h1>

Answer 3

An alternative to Andy answer, using Set

Since adding an existing value to a Set does effectively nothing, this keeps adding values to the set until the size reaches the required count

Warning: It's naive code that doesn't check that count greater than the possible values

 function sorteio() { const getRandom = (min, max, count) => { const result = new Set; while (result.size < count) { result.add(Math.floor(Math.random() * (max - min + 1)) + min); } return [...result]; } const gerarNumerosEntre1a60 = n => { const resultado = getRandom(1, 60, n); return resultado; } document.getElementById("resultado").innerHTML = gerarNumerosEntre1a60(6); }

 <button onclick="sorteio()">Sortear numeros!</button> <h1 id="resultado"></h1>