JavaScript generate random numbers without repeating

问题

I have some code where I have an array of x amount of items. In this case, videos, and I want to randomly call a video, however if the current video already called is the same as the random number I want it to generate another random number until it's unique.

Here's my code:

var videoLinks = [
    ['<iframe id="vid" src="https://www.youtube.com/embed/nYm2G4MnSkY?autoplay=1" frameborder="0" allowfullscreen></iframe>'],
    ['<iframe id="vid" src="https://www.youtube.com/embed/wAgZVLk6J4M?autoplay=1&start=5&end=45" frameborder="0" allowfullscreen></iframe>'],
    ['<iframe id="vid" src="https://www.youtube.com/embed/ix9wpslKwBE?autoplay=1" frameborder="0" allowfullscreen></iframe>'],
    ['<iframe id="vid" src="https://www.youtube.com/embed/OJJ-iLsQOPc?autoplay=1&iv_load_policy=3" frameborder="0" allowfullscreen></iframe>'],
    ['<iframe id="vid" src="https://www.youtube.com/embed/rore790l_sk?autoplay=1&start=12&end=94" frameborder="0" allowfullscreen></iframe>'],
];

var randomNumber = function () {
    var getRandomNumber = Math.floor(Math.random() * 5);
    var random = videoLinks[getRandomNumber]
    document.getElementById("videoWrapper").innerHTML = random[0];
};

randomNumber(); // To call the function on load

回答1:

use a variable to check if the number is the same.

something like this: (using LastNumber to store the lastNumber) if it allready is used we gonna try again)

var videoLinks = [
    ....
];

var lastNumber = 0;
var randomNumber = function () {
    var getRandomNumber = Math.floor(Math.random() * 5);  
    if(getRandomNumber != lastNumber){
        var random = videoLinks[getRandomNumber];
        document.getElementById("videoWrapper").innerHTML = random[0];
        lastNumber = getRandomNumber;
    }else{
        randomNumber();
    }
};

randomNumber(); // To call the function on load

回答2:

You can create an array to keep the exiting generated numbers.

var existingNumbers = [];
var maxNumbers = 5;
var randomNumber = function() {
  if (existingNumbers.length != maxNumbers) {
    do {
      getRandomNumber = Math.floor(Math.random() * maxNumbers);
    } while (existingNumbers.indexOf(getRandomNumber) > -1);
    existingNumbers.push(getRandomNumber);
   
    var random = videoLinks[getRandomNumber]
    document.getElementById("videoWrapper").innerHTML = random[0];
  }
};

回答3:

First of all, why do you wrap all those strings in Arrays? I dropped them in my solution below. Anyway, easiest and cleanest solution is to clone the Array, and drop the selected URL from the new Array.

var videoLinks = [
    '<iframe id="vid" src="https://www.youtube.com/embed/nYm2G4MnSkY?autoplay=1" frameborder="0" allowfullscreen></iframe>',
    '<iframe id="vid" src="https://www.youtube.com/embed/wAgZVLk6J4M?autoplay=1&start=5&end=45" frameborder="0" allowfullscreen></iframe>',
    '<iframe id="vid" src="https://www.youtube.com/embed/ix9wpslKwBE?autoplay=1" frameborder="0" allowfullscreen></iframe>',
    '<iframe id="vid" src="https://www.youtube.com/embed/OJJ-iLsQOPc?autoplay=1&iv_load_policy=3" frameborder="0" allowfullscreen></iframe>',
    '<iframe id="vid" src="https://www.youtube.com/embed/rore790l_sk?autoplay=1&start=12&end=94" frameborder="0" allowfullscreen></iframe>'
];
var temp = videoLinks.slice();

function randomVideo(){
  var r = Math.floor(Math.random()*temp.length);
  return temp.splice(r, 1);
}

来源：https://stackoverflow.com/questions/32587165/javascript-generate-random-numbers-without-repeating

标签

javascript

random

numbers