[英]Getting a 40 random values from a JavaScript array, Quizz App. I have in another file questions.js 3000 questions, I want to get random 40 questions
I want to get unique random 40 questions from questions.js anyone have suggestions.我想从 questions.js 中获得独特的随机 40 个问题,任何人都有建议。
//show Questions from array
function showQuetions(index) {
const que_text = document.querySelector(".que_text");
//question tag add questions from another file
let que_tag = '<span>' + questions[index].numb + ". " + questions[index].question + '</span>';
let option_tag = '<div class="option"><span>' + questions[index].options[0] + '</span></div>' +
'<div class="option"><span>' + questions[index].options[1] + '</span></div>' +
'<div class="option"><span>' + questions[index].options[2] + '</span></div>' +
'<div class="option"><span>' + questions[index].options[3] + '</span></div>';
que_text.innerHTML = que_tag;
option_list.innerHTML = option_tag;
const option = option_list.querySelectorAll(".option");
for (i = 0; i < option.length; i++) {
option[i].setAttribute("onclick", "optionSelected(this)");
}
}
The are multiples ways to do that :有多种方法可以做到这一点:
The first method would be to shuffle the array and the take the first 40 questions.第一种方法是打乱数组并回答前 40 个问题。
You can write a pretty simple methods that suffle your array How can I shuffle an array您可以编写一个非常简单的方法来调整您的数组How can I shuffle an array
You can also take 40 random elements (by taking a random integer between 0 and the number of questions you have and then removing that questions from the array.您还可以采用 40 个随机元素(通过采用0和您所拥有的问题数量之间的随机整数,然后从数组中删除这些问题。
Be sure to make a deep copy of the array before doing this在执行此操作之前,请务必对数组进行深拷贝
copy = Object.assign([],questions)
Then, do not forget to remove the question from the array to ensure not having the same question twice然后,不要忘记从数组中删除问题以确保没有两次相同的问题
Here is a snipper with both example :这是一个带有两个示例的狙击手:
/** * Shuffles array in place. * @param {Array} a items An array containing the items. * From https://stackoverflow.com/questions/6274339/how-can-i-shuffle-an-array */ function shuffle(a) { var j, x, i; for (i = a.length - 1; i > 0; i--) { j = Math.floor(Math.random() * (i + 1)); x = a[i]; a[i] = a[j]; a[j] = x; } return a; } const nbQuestions = 2 const questions = ["question 1","question 2","question 3","question 4","question 5","question 6"] //method 1 //deep copy let method1Questions = Object.assign([],questions) shuffle(method1Questions) let randomQuestions1 = method1Questions.slice(0,nbQuestions) console.log(randomQuestions1) //method 2 //deep copy let method2Questions = Object.assign([],questions) let randomQuestions2 = [] for (let i=0; i < nbQuestions; i++){ //random int let questionIndex = Math.floor(Math.random() * method2Questions.length) randomQuestions2.push(method2Questions[questionIndex]) method2Questions.splice(questionIndex,1) } console.log(randomQuestions2)
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