Javascript generate random string

// Generate a random alphanumerical string of length 11 ( change substring parameter for other length)
Math.random().toString(36).substring(2);function getRandomString(length) {
    var randomChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var result = '';
    for ( var i = 0; i < length; i++ ) {
        result += randomChars.charAt(Math.floor(Math.random() * randomChars.length));
    }
    return result;
}

//usage: getRandomString(20); // pass desired length of random stringconst string_length = 10
[...Array(string_length)].map(i=>(~~(Math.random()*36)).toString(36)).join('')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;
}

console.log(makeid());
var crypto = require("crypto");
var id = crypto.randomBytes(20).toString('hex');

// "bb5dc8842ca31d4603d6aa11448d1654" Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15);