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devel
packages/random/NodeRandomGenerator.js
37 строк
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sebakerckhof
Refactor types into strategy-pattern (ish) subclasses.
25 фев 2020, 12:39
25 фев 2020, 12:39
f093036
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import crypto from 'crypto'; import RandomGenerator from './AbstractRandomGenerator'; export default class NodeRandomGenerator extends RandomGenerator { /** * @name Random.fraction * @summary Return a number between 0 and 1, like `Math.random`. * @locus Anywhere */ fraction () { const numerator = Number.parseInt(this.hexString(8), 16); return numerator * 2.3283064365386963e-10; // 2^-3; } /** * @name Random.hexString * @summary Return a random string of `n` hexadecimal digits. * @locus Anywhere * @param {Number} n Length of the string */ hexString (digits) { const numBytes = Math.ceil(digits / 2); let bytes; // Try to get cryptographically strong randomness. Fall back to // non-cryptographically strong if not available. try { bytes = crypto.randomBytes(numBytes); } catch (e) { // XXX should re-throw any error except insufficient entropy bytes = crypto.pseudoRandomBytes(numBytes); } const result = bytes.toString('hex'); // If the number of digits is odd, we'll have generated an extra 4 bits // of randomness, so we need to trim the last digit. return result.substring(0, digits); } }