如何修复JavaScript中从随机选中数组取随机值的错误？

问题根源 #

你当前的代码中，winningArray拿到的是数组名称的字符串（比如"sixMatched"），而非实际的数组变量。因此当你用winningArray[下标]时，实际是在取字符串的某个字符，而非数组元素。

推荐修复方法：用对象统一管理数组 #

最规范的做法是把所有匹配数组放到一个对象中，通过字符串键名直接获取对应的数组引用：

步骤1：重构数据结构 #

把四个数组包裹到一个对象里，替代原来的独立变量：

// 用对象统一管理所有匹配数组
var matchArrays = {
  sixMatched: ["367687"],
  fiveMatched: ["567687","337687","167687","367587","368687"],
  fourMatched: ["387087","357187","365627","367620","369627","867987","367610","367604","394687","397681","367247","167683","767697","567617","367207"],
  threeMatched: ["338680","965647","163637","333677","837637","267427","364288","357634","767817","361557","302682","667027","320637","547686","967088","382637","360167","327286","817187","707087","387481","357280","563287","367803","867646","277686","384697","364483","467827","332681"]
};

// 保留原有的数组名称列表
var selectedArray = ["sixMatched","fiveMatched","fourMatched","threeMatched"];

步骤2：修改点击事件代码 #

通过对象的键名获取实际数组，再从中随机选取元素：

$('#play').click(function(){
    // 随机选取数组名称字符串
    var winningArrayName = selectedArray[Math.floor(Math.random()*selectedArray.length)];
    // 通过对象键名获取对应的数组
    var winningArray = matchArrays[winningArrayName];
    // 从数组中随机选取数字
    var winningNumber = winningArray[Math.floor(Math.random()*winningArray.length)];
    
    // 注意：animateNumber需要数字类型，所以把字符串转成整数
    $('#number').animateNumber({ number: parseInt(winningNumber) });
    console.log("Winning array is "+ winningArrayName +"");
    console.log("Winning number is "+ winningNumber +"");
    return false;   
});

替代方案（不推荐）：直接访问全局变量 #

如果不想重构数据结构，也可以通过window对象访问全局变量（你原来的数组都是全局变量），但这种方法容易引发变量冲突，不利于代码维护：

$('#play').click(function(){
    var winningArrayName = selectedArray[Math.floor(Math.random()*selectedArray.length)];
    // 从window对象中获取对应的数组
    var winningArray = window[winningArrayName];
    var winningNumber = winningArray[Math.floor(Math.random()*winningArray.length)];
    
    $('#number').animateNumber({ number: parseInt(winningNumber) });
    console.log("Winning array is "+ winningArrayName +"");
    console.log("Winning number is "+ winningNumber +"");
    return false;   
});

内容的提问来源于stack exchange，提问作者TheWalkdenDead