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UUID v4 implementation in JavaScript
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| /* | |
| Paraphrased from RFC 4122: | |
| The formal definition of the UUID string representation is | |
| provided by the following ABNF: | |
| UUID = time-low "-" time-mid "-" | |
| time-high-and-version "-" | |
| clock-seq-and-reserved | |
| clock-seq-low "-" node | |
| time-low = 4hexOctet | |
| time-mid = 2hexOctet | |
| time-high-and-version = 2hexOctet | |
| clock-seq-and-reserved = hexOctet | |
| clock-seq-low = hexOctet | |
| node = 6hexOctet | |
| hexOctet = hexDigit hexDigit | |
| hexDigit = | |
| "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" / | |
| "a" / "b" / "c" / "d" / "e" / "f" / | |
| "A" / "B" / "C" / "D" / "E" / "F" | |
| The version 4 UUID is meant for generating UUIDs from truly-random or | |
| pseudo-random numbers. | |
| The algorithm is as follows: | |
| - Set the two most significant bits (bits 6 and 7) of the | |
| clock-seq-and-reserved to zero and one, respectively. | |
| - Set the four most significant bits (bits 12 through 15) of the | |
| time-high-and-version field to 0100 | |
| - Set all the other bits to randomly (or pseudo-randomly) chosen | |
| values. | |
| */ | |
| function uuidV4() { | |
| const uuid = new Array(36); | |
| for (let i = 0; i < 36; i++) { | |
| uuid[i] = Math.floor(Math.random() * 16); | |
| } | |
| uuid[14] = 4; // set bits 12-15 of time-high-and-version to 0100 | |
| uuid[19] = uuid[19] &= ~(1 << 2); // set bit 6 of clock-seq-and-reserved to zero | |
| uuid[19] = uuid[19] |= (1 << 3); // set bit 7 of clock-seq-and-reserved to one | |
| uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-'; | |
| return uuid.map((x) => x.toString(16)).join(''); | |
| } | |
| module.exports = uuidV4; |
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