JavaScript to create a random string method with numeric letters summary _javascript Tips

First type:

The code from http://caibaojian.com/js-random-string.html
function Makeid ()
{
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (Var i=0 i < 5; i++)
    text + possible.charat (Math.floor (Math.random () * possible.length));

  return text;

Second: Do not need to enter the character set together

function RandomString (L) {
  var s= ';
  var randomchar=function () {
   var n= math.floor (Math.random () *62);
   if (n<10) return n; 1-10
   if (n<36) return String.fromCharCode (n+55),//a-z return
   string.fromcharcode (n+61);//a-z
  } While
  (s.length< L) s+= Randomchar ();
  return s;
}

alert(randomstring(5))

Third: Supports custom character length and feature character set combination

function RandomString (len, charSet) {
  CharSet = CharSet | | ' ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 ';
  var randomstring = ';
  for (var i = 0; i < len; i++) {
   var randompoz = Math.floor (Math.random () * charset.length);
   RandomString + = charset.substring (randompoz,randompoz+1);
  }
  return randomstring;
}

Call with default CharSet [a-za-z0-9] or send in your own:

var randomvalue = RandomString (5);

var randomvalue = randomstring (5, ' pickcharsfromthisset ');

Demo screenshot

The above is JavaScript to create a random string with digital letters three methods summary, there is a need to reference learning.