\n\n[](https://travis-ci.org/ulid/javascript) [](https://codecov.io/gh/ulid/javascript)\n[](https://www.npmjs.com/package/ulid)\n\n# Universally Unique Lexicographically Sortable Identifier\n\nUUID can be suboptimal for many uses-cases because:\n\n- It isn't the most character efficient way of encoding 128 bits of randomness\n- UUID v1/v2 is impractical in many environments, as it requires access to a unique, stable MAC address\n- UUID v3/v5 requires a unique seed and produces randomly distributed IDs, which can cause fragmentation in many data structures\n- UUID v4 provides no other information than randomness which can cause fragmentation in many data structures\n\nInstead, herein is proposed ULID:\n\n- 128-bit compatibility with UUID\n- 1.21e+24 unique ULIDs per millisecond\n- Lexicographically sortable!\n- Canonically encoded as a 26 character string, as opposed to the 36 character UUID\n- Uses Crockford's base32 for better efficiency and readability (5 bits per character)\n- Case insensitive\n- No special characters (URL safe)\n- Monotonic sort order (correctly detects and handles the same millisecond)\n\n## Installation\n\n```\nnpm install --save ulid\n```\n\n## Import\n\n**TypeScript, ES6+, Babel, Webpack, Rollup, etc.. environments**\n```javascript\nimport { ulid } from 'ulid'\n\nulid() // 01ARZ3NDEKTSV4RRFFQ69G5FAV\n```\n\n**CommonJS environments**\n```javascript\nconst ULID = require('ulid')\n\nULID.ulid()\n```\n\n**AMD (RequireJS) environments**\n```javascript\ndefine(['ULID'] , function (ULID) {\n ULID.ulid()\n});\n```\n\n**Browser**\n```html\n\n\n```\n\n## Usage\n\nTo generate a ULID, simply run the function!\n\n```javascript\nimport { ulid } from 'ulid'\n\nulid() // 01ARZ3NDEKTSV4RRFFQ69G5FAV\n```\n\n### Seed Time\n\nYou can also input a seed time which will consistently give you the same string for the time component. This is useful for migrating to ulid.\n\n```javascript\nulid(1469918176385) // 01ARYZ6S41TSV4RRFFQ69G5FAV\n```\n\n### Monotonic ULIDs\n\nTo generate monotonically increasing ULIDs, create a monotonic counter.\n\n*Note that the same seed time is being passed in for this example to demonstrate its behaviour when generating multiple ULIDs within the same millisecond*\n\n```javascript\nimport { monotonicFactory } from 'ulid'\n\nconst ulid = monotonicFactory()\n\n// Strict ordering for the same timestamp, by incrementing the least-significant random bit by 1\nulid(150000) // 000XAL6S41ACTAV9WEVGEMMVR8\nulid(150000) // 000XAL6S41ACTAV9WEVGEMMVR9\nulid(150000) // 000XAL6S41ACTAV9WEVGEMMVRA\nulid(150000) // 000XAL6S41ACTAV9WEVGEMMVRB\nulid(150000) // 000XAL6S41ACTAV9WEVGEMMVRC\n\n// Even if a lower timestamp is passed (or generated), it will preserve sort order\nulid(100000) // 000XAL6S41ACTAV9WEVGEMMVRD\n```\n\n### Pseudo-Random Number Generators\n\n`ulid` automatically detects a suitable (cryptographically-secure) PRNG. In the browser it will use `crypto.getRandomValues` and on node it will use `crypto.randomBytes`.\n\n#### Allowing the insecure `Math.random`\n\nBy default, `ulid` will not use `Math.random`, because that is insecure. To allow the use of `Math.random`, you'll have to use `factory` and `detectPrng`.\n\n```javascript\nimport { factory, detectPrng } from 'ulid'\n\nconst prng = detectPrng(true) // pass `true` to allow insecure\nconst ulid = factory(prng)\n\nulid() // 01BXAVRG61YJ5YSBRM51702F6M\n```\n\n#### Use your own PRNG\n\nTo use your own pseudo-random number generator, import the factory, and pass it your generator function.\n\n```javascript\nimport { factory } from 'ulid'\nimport prng from 'somewhere'\n\nconst ulid = factory(prng)\n\nulid() // 01BXAVRG61YJ5YSBRM51702F6M\n```\n\nYou can also pass in a `prng` to the `monotonicFactory` function.\n\n```javascript\nimport { monotonicFactory } from 'ulid'\nimport prng from 'somewhere'\n\nconst ulid = monotonicFactory(prng)\n\nulid() // 01BXAVRG61YJ5YSBRM51702F6M\n```\n\n## Implementations in other languages\n\nRefer to [ulid/spec](https://github.com/ulid/spec)\n\n## Specification\n\nRefer to [ulid/spec](https://github.com/ulid/spec)\n\n## Test Suite\n\n```\nnpm test\n```\n\n## Performance\n\n```\nnpm run perf\n```\n\n```\nulid\n336,331,131 op/s » encodeTime\n102,041,736 op/s » encodeRandom\n17,408 op/s » generate\n\n\nSuites: 1\nBenches: 3\nElapsed: 7,285.75 ms\n```\n","_attachments":{},"homepage":"https://github.com/ulid/javascript#readme","bugs":{"url":"https://github.com/ulid/javascript/issues"},"license":"MIT"}
![\"ulid\"](\"logo.png\")
\n\t