function generate(length) {
  var letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","0","1","2","3","4","5","6","7","8","9"];
  var IDtext = "";
  var i = 0;
  while (i < length) {
    var letterIndex = Math.floor(Math.random() * letters.length);
    var letter = letters[letterIndex];
    IDtext = IDtext + letter;
    i++;
  }
  console.log(IDtext)
}

这一个结合了许多给出的答案。

var randNo=Math.floor（Math.random（）*100）+2+“”+new Date（）.getTime（）+Math.floof（Math.rrandom（）*100）+2+（Math.rand（）.toString（36）.replace（/[^a-zA-Z]+/g，''）.substr（0，5））；console.log（randNo）；

我用了一个月，效果很好。

带有es6排列运算符的更新版本：

[…数组（30）].map（（）=>Math.random（）.toString（36）[2]）.join（“”）

30是一个任意数字，您可以选择所需的任何令牌长度36是可以传递给numeric.toString（）的最大基数，表示所有数字和a-z小写字母2用于从如下所示的随机字符串中选择第三个索引：“0.mfbiohx64i”，我们可以取0之后的任何索引。

",,,,,".replace(/,/g,function (){return "AzByC0xDwEv9FuGt8HsIrJ7qKpLo6MnNmO5lPkQj4RiShT3gUfVe2WdXcY1bZa".charAt(Math.floor(Math.random()*62))});

这是我创建的方法。它将创建一个包含大小写字符的字符串。此外，我还包含了将创建字母数字字符串的函数。

工作示例：http://jsfiddle.net/greatbigmassive/vhsxs/（仅限alpha）http://jsfiddle.net/greatbigmassive/PJwg8/（字母数字）

function randString(x){
    var s = "";
    while(s.length<x&&x>0){
        var r = Math.random();
        s+= String.fromCharCode(Math.floor(r*26) + (r>0.5?97:65));
    }
    return s;
}

2015年7月升级这做了同样的事情，但更有意义，包括所有字母。

var s = "";
while(s.length<x&&x>0){
    v = Math.random()<0.5?32:0;
    s += String.fromCharCode(Math.round(Math.random()*((122-v)-(97-v))+(97-v)));
}

"12345".split('').map(function(){return 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'.charAt(Math.floor(62*Math.random()));}).join('');

//or

String.prototype.rand = function() {return this.split('').map(function(){return 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'.charAt(Math.floor(62*Math.random()));}).join('');};

将生成长度为第一个/调用字符串的随机字母数字字符串