Generating truly random numbers in Javascript

Question

Is it possible to create a truly random number in JavaScript?

I have tried here jsfiddle

Javascript:

    // Mouse coordinates on click
var mouseX;
var mouseY;
$(document).ready(function(){

  $("#btn1").click(function(e){
    mouseX = e.clientX;
    mouseY = e.clientY;
  });

});


// Timing mouse down
var pressed;
var duration;

$(document).ready(function(){

  $("#btn1").on("mousedown", function(){
    pressed = +new Date();
  });
  $("#btn1").on("mouseup", function(){
    duration = +new Date() - pressed;
  });

});

// Time since last click
var loaded;
var onPush;
$(document).ready(function(){

  loaded = +new Date();
  $("#btn1").on("mousedown", function(){
    onPush = +new Date() - loaded;
    loaded = +new Date();
  });

});

// Extending process for pseudorandom number? or creating a truly random number?
$(document).ready(function(){
  $("#btn1").on("click", function(){

    function rnum(min, max) {
      var a = Math.random();
      var ranMouseX = mouseX * a;
      var ranMouseY = mouseY * a;
      var ranDuration = duration * a;
      var ranOnPush = onPush * a;

      var combine = ((ranMouseX / ranOnPush) + (ranMouseY / ranDuration) % a);
      $("#p1").text(((combine - Math.floor(combine)) * (max-min) + min).toFixed(0))
    };
    var f = document.getElementById('min');
    var g = document.getElementById('max');
    rnum(parseInt(f.value), parseInt(g.value));
  });
});

But have I just extended the process for a pseudo-random number? or does this make a truly random number?

If it is still just a pseudo-random number how can I make a truly random number in JavaScript?

truly random numbers require a truly random source of noise, usually physical....Trying to make your own 'more' random numbers invariably leads to generating something less random! Random number generation is best left to the experts. — Mitch Wheat
– Mitch Wheat, Commented Mar 23, 2017 at 3:40
Math.random() is just fine, don't really understand what you're looking for. From that original random number, just perform some calculation/computation to get your own random numbers (with such as greater values, ...). — King King
– King King, Commented Mar 23, 2017 at 3:45
developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — c.k
– c.k, Commented Mar 23, 2017 at 3:47
Beyond the emotional satisfaction of saying "truly random" -- what are you trying to accomplish? It is a fairly deep area. JavaScript's PRNG is adequate for most purposes (though it does fall short of e.g. Python's). You could always implement your own version of e.g. the Mersenne Twister -- but do you really need it? This is interesting: v8project.blogspot.com/2015/12/… — John Coleman
– John Coleman, Commented Mar 23, 2017 at 3:49

Kaiido · Accepted Answer · 2017-03-23 03:54:46Z

3

From default APIs, you'll be stuck with pseudo-random (truly random would require a physical interface).

However, the Crypto interface does provide a crypto-safe random number generator : Crypto.getRandomValues() which seeds have more entropy than the default Math.random() method.

var array = new Uint32Array(10);
window.crypto.getRandomValues(array);

for (var i = 0; i < array.length; i++) {
    console.log(array[i]);
}

answered Mar 23, 2017 at 3:54

Kaiido

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1 Comment

S To Over a year ago

How can I use this to hex 64 characters of Hex Values?

asparism · Accepted Answer · 2017-12-17 10:14:03Z

1

There is an API - ANU Quantum Random Number Generator API that you can use. From the description:

The numbers are considered to be "truly random", because they are generated by measuring the quantum fluctuations of a vacuum

answered Dec 17, 2017 at 10:14

asparism

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