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40 lines
1.4 KiB
TypeScript
40 lines
1.4 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// Copyright 2023 Yoshiya Hinosawa. All rights reserved. MIT license.
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// Copyright 2017 Alizain Feerasta. All rights reserved. MIT license.
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// This module is browser compatible.
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import { encodeRandom, encodeTime } from "./_util.ts";
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/**
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* Generate a ULID, optionally based on a given timestamp. If the timestamp is
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* not passed, it will default to `Date.now()`.
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*
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* Multiple calls to this function with the same seed time will not guarantee
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* that the ULIDs will be strictly increasing, even if the seed time is the
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* same. For that, use the {@linkcode monotonicUlid} function.
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*
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* @example Generate a ULID
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* ```ts no-assert
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* import { ulid } from "@std/ulid";
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*
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* ulid(); // 01HYFKMDF3HVJ4J3JZW8KXPVTY
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* ulid(); // 01HYFKMDF3D2P7G502B9Z2VKV0
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* ulid(); // 01HYFKMDZQ7JD17CRKDXQSZ3Z4
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* ```
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*
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* @example Generate a ULID with a seed time
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* ```ts no-assert
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* import { ulid } from "@std/ulid";
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*
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* ulid(150000); // 0000004JFG3EKDRE04TVVDJW7K
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* ulid(150000); // 0000004JFGN0KHBH0447AK895X
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* ulid(150000); // 0000004JFGMRDH0PN7SM8BZN06
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* ```
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*
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* @param seedTime The time to base the ULID on, in milliseconds since the Unix epoch. Defaults to `Date.now()`.
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* @returns A ULID.
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*/
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export function ulid(seedTime: number = Date.now()): string {
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return encodeTime(seedTime) + encodeRandom();
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}
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