Question 294994 in Javascript Question posted in
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Javascript – How to optimize search of unasked questions?

Currently I have the following code –

var questions = ['1', '2', '3', '4', ..., 'n'];
var qAsked = []; // array of indexes of already asked questions

//  the code below is executed multiple times
if (typeof $qAsked == "undefined") || ($qAsked.length < $questions.length) { // if not all questions asked

    // the code below looks for questions, which were NOT asked before
    var qCount = $questions.length-1;
    var qIndex = Math.floor(Math.random() * qCount);

    while ($qAsked[$category].indexOf(qIndex) > -1) { // avoid repeated questions
      qIndex = Math.floor(Math.random() * qCount);
    }
    qAsked.push(qIndex);
    q = $questions[qIndex];
 }

The array contains ~150 elements, but executions of the code takes a lot of time.
Is there any way to optimize this code?

Tags:

3

Answers


  1. 0

    Splice the original array and get the desired output, if you dont want to touch the original array, just destructure it into a new array.

    var questions = ['1', '2', '3', '4', '5', 'n'];

const askQuestion = () => {
  if(!questions.length) {
    return 'out of questions!';
  }
  const index = Math.floor(getRandomInt(0, questions.length));
  return questions.splice(index,1)[0];
}

function getRandomInt(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min) + min); 
}

console.log(askQuestion());
console.log(askQuestion());
console.log(askQuestion());
console.log(askQuestion());
console.log(askQuestion());
console.log(askQuestion());
console.log(askQuestion());
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  2. 0

    Why not just shuffle the questions (or create a shuffled copy) and then ask them one by one:

    var questions = ['1', '2', '3', '4', '5', 'n'];
var shuffledQuerytions = shuffle(questions.slice());

function shuffle(array) {
  for (let i = array.length, j, tmp; i > 1;) {
    j = Math.floor(Math.random() * i--);
    tmp = array[i];
    array[i] = array[j];
    array[j] = tmp;
  }
  return array;
}

for (const q of shuffledQuerytions) {
  console.log(q);
}
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  3. 0

    You can use this algorithm to shuffle your array and then iterate through it sequentially.

    function shuffleArray(array) {
    for (var i = array.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
}

shuffleArray(questions);

var qIndex = 0;
var q = questions[qIndex];
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