如何生成有条件的随机物品？

问题描述

我正在一个项目中，我需要生成一个数组的十六个随机元素。我需要确保随机数中的两个恰好是给定的元素，但是我不希望它们每次都位于同一位置。有没有一种方法可以从数组中生成随机项目，但是可以保证其中两个随机项目将成为特定元素？

<div id = "choice1">
<div id = "choice2">
<div id = "choice3">
<div id = "choice4">
<div id = "choice5">
<div id = "choice6">
<div id = "choice7">
<div id = "choice8">
<div id = "choice9">
<div id = "choice10">
<div id = "choice11">
<div id = "choice12">
<div id = "choice13">
<div id = "choice14">
<div id = "choice15">
<div id = "choice16">

var elem = ["a","b","c","d"...];
var o1 = Math.floor(Math.random() * elem.length);
var obj1 = elem[o1];
document.getElementById("choice1").innerHTML = obj1;
...

解决方法

您可以像这样（从this post改编而来）在普通JavaScript中执行此操作：

//"pre-select" required elements
var selectedElementIDs = ["choice1","choice2"];

//define other possible elements
var otherPossibleElementIDs = ["choice3","choice4","choice5","choice6","choice7","choice8","choice9","choice10","choice11","choice12","choice13","choice14","choice15","choice16"];

//"select" 3 more elements from the "possible elements" array
for (var i = 0; i < 3; i++) selectedElementIDs.push(otherPossibleElementIDs.splice(Math.floor(Math.random() * otherPossibleElementIDs.length),1)[0]);

//shuffle your selections so the "pre-selected" required elements aren't always first
var j,x,i;
for (i = selectedElementIDs.length - 1; i > 0; i--) {
  j = Math.floor(Math.random() * (i + 1));
  x = selectedElementIDs[i];
  selectedElementIDs[i] = selectedElementIDs[j];
  selectedElementIDs[j] = x;
}

//log the result to the console to show it worked
console.log(selectedElementIDs);

或者，如果愿意，您可以使用rando.js以更易于理解（且加密安全）的方式进行此操作：

//"pre-select" required elements
var selectedElementIDs = ["choice1","choice2"];

//define other possible elements (and go ahead and shuffle them so "popping" from that array after this will produce a random next value)
var otherPossibleElementIDs = randoSequence(["choice3","choice16"]);

//"select" 3 more elements from the "possible elements" array
for(var i = 0; i < 3; i++) selectedElementIDs.push(otherPossibleElementIDs.pop().value);

//shuffle your selections so the "pre-selected" required elements aren't always first
selectedElementIDs = randoSequence(selectedElementIDs);
for(var i = 0; i < selectedElementIDs.length; i++) selectedElementIDs[i] = selectedElementIDs[i].value;

//log the result to the console to show it worked
console.log(selectedElementIDs);

<script src="https://randojs.com/2.0.0.js"></script>