js generate 20 long random alphanumeric code example

Example 1: create random 4 digit number js

var val = Math.floor(1000 + Math.random() * 9000);
console.log(val);

Example 2: javascript random no between 2 numbers

function randomIntFromInterval(min, max) { // min and max included 
  return Math.floor(Math.random() * (max - min + 1) + min);
}