34 lines
1.3 KiB
JavaScript
34 lines
1.3 KiB
JavaScript
// Unique ID creation requires a high quality random # generator. In the
|
|
// browser this is a little complicated due to unknown quality of Math.random()
|
|
// and inconsistent support for the `crypto` API. We do the best we can via
|
|
// feature-detection
|
|
|
|
// getRandomValues needs to be invoked in a context where "this" is a Crypto
|
|
// implementation. Also, find the complete implementation of crypto on IE11.
|
|
var getRandomValues = (typeof(crypto) != 'undefined' && crypto.getRandomValues && crypto.getRandomValues.bind(crypto)) ||
|
|
(typeof(msCrypto) != 'undefined' && typeof window.msCrypto.getRandomValues == 'function' && msCrypto.getRandomValues.bind(msCrypto));
|
|
|
|
if (getRandomValues) {
|
|
// WHATWG crypto RNG - http://wiki.whatwg.org/wiki/Crypto
|
|
var rnds8 = new Uint8Array(16); // eslint-disable-line no-undef
|
|
|
|
module.exports = function whatwgRNG() {
|
|
getRandomValues(rnds8);
|
|
return rnds8;
|
|
};
|
|
} else {
|
|
// Math.random()-based (RNG)
|
|
//
|
|
// If all else fails, use Math.random(). It's fast, but is of unspecified
|
|
// quality.
|
|
var rnds = new Array(16);
|
|
|
|
module.exports = function mathRNG() {
|
|
for (var i = 0, r; i < 16; i++) {
|
|
if ((i & 0x03) === 0) r = Math.random() * 0x100000000;
|
|
rnds[i] = r >>> ((i & 0x03) << 3) & 0xff;
|
|
}
|
|
|
|
return rnds;
|
|
};
|
|
}
|