Quick Math.random() wrapper with support for window.crypto.getRandomValues

random.js

// Math.random() wrapper with support for window.crypto.getRandomValues
// return a random number, 0 <= rand() < 1
function rand() {
  if (window.crypto && window.crypto.getRandomValues && (typeof Uint8Array=='function')) {
    var buf = new Uint8Array(4);
    window.crypto.getRandomValues(buf);
    // buf = [0,0,0,0];         // 0
    // buf = [255,255,255,255]; // closest to 1
    // buf = [0,0,0,128];       // < 0.5
    // buf = [1,0,0,128];       // > 0.5
    var v = ((buf[3]<<24) | (buf[2]<<16) | (buf[1]<<8) | buf[0])/0xffffffff;
    return v<0 ? v+1 : v;
  } else {
    return Math.random();
  }
}

// Minified:
// function rand(){if(window.crypto&&window.crypto.getRandomValues&&"function"==typeof Uint8Array){var A=new Uint8Array(4);window.crypto.getRandomValues(A);var o=(A[3]<<24|A[2]<<16|A[1]<<8|A[0])/0xffffffff;return 0>o?o+1:o}return Math.random()}