Instead of Math.random(), you can use crypto.getRandomValues() to generate evenly-distributed cryptographically-secure random numbers. Here's an example:
function randInt(min, max) {
var MAX_UINT32 = 0xFFFFFFFF;
var range = max - min;
if (!(range <= MAX_UINT32)) {
throw new Error(
"Range of " + range + " covering " + min + " to " + max + " is > " +
MAX_UINT32 + ".");
} else if (min === max) {
return min;
} else if (!(max > min)) {
throw new Error("max (" + max + ") must be >= min (" + min + ").");
}
// We need to cut off values greater than this to avoid bias in distribution
// over the range.
var maxUnbiased = MAX_UINT32 - ((MAX_UINT32 + 1) % (range + 1));
var rand;
do {
rand = crypto.getRandomValues(new Uint32Array(1))[0];
} while (rand > maxUnbiased);
var offset = rand % (range + 1);
return min + offset;
}
console.log(randInt(-8, 8)); // -2
console.log(randInt(0, 0)); // 0
console.log(randInt(0, 0xFFFFFFFF)); // 944450079
console.log(randInt(-1, 0xFFFFFFFF));
// Uncaught Error: Range of 4294967296 covering -1 to 4294967295 is > 4294967295.
console.log(new Array(24).fill().map(n => randInt(8, 12)));
// [11, 8, 8, 11, 10, 8, 8, 12, 12, 12, 9, 9,
// 11, 8, 11, 8, 8, 8, 11, 9, 10, 12, 9, 11]
console.log(randInt(10, 8));
// Uncaught Error: max (8) must be >= min (10).