Reduce length of generateStrongCompactUuid

Waveful · Apr 9, 2022 · 79e85b7 · 79e85b7
1 parent 46a71af
commit 79e85b7
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Showing 3 changed files with 13 additions and 13 deletions.
diff --git a/README.md b/README.md
@@ -40,7 +40,7 @@ ES6 module syntax:
 import { generateCustomUuid, generateShortUuid, generateStrongCompactUuid } from "custom-uuid";
 generateCustomUuid("123456789ABC", 20); // ⇨ 'C12B1B2A9382A488B43A'
 generateShortUuid(); // ⇨ 'yT1xoeCt6fvdDf6a'
-generateStrongCompactUuid(); // ⇨ 'BYFGhRjnn83hHCarT09HKJ'
+generateStrongCompactUuid(); // ⇨ 'BYFGhRjnn83hHCarT09H'
 ```
 
 CommonJS syntax:
@@ -49,7 +49,7 @@ CommonJS syntax:
 const { generateCustomUuid, generateShortUuid, generateStrongCompactUuid } = require('custom-uuid');
 generateCustomUuid("123456789ABC", 20); // ⇨ 'B5B6699247862A569998'
 generateShortUuid(); // ⇨ 'DMDvkPec8QUyV9O1'
-generateStrongCompactUuid(); // ⇨ 'xRC4JggRQQFdPwn6MhZs08'
+generateStrongCompactUuid(); // ⇨ 'xRC4JggRQQFdPwn6MhZs'
 ```
 
 #### 3. Make sure the custom UUID is unique enough for your use case
@@ -69,7 +69,7 @@ Or you can use one of the pre-defined UUIDs that have strong guarantees of uniqu
 | Method                                                                                        | Length | Example output                         |
 |-----------------------------------------------------------------------------------------------|--------|----------------------------------------|
 | [`generateShortUuid()`](#generateShortUuid)                                                   | 16     | `14usBY8xSYXGPvsA`                     |
-| [`generateStrongCompactUuid()`](#generateStrongCompactUuid)                                   | 22     | `6ptGBhTKkxTMCMEiiHiwwj`               |
+| [`generateStrongCompactUuid()`](#generateStrongCompactUuid)                                   | 20     | `6ptGBhTKkxTMCMEiiHiw`                 |
 | [`generateShortLowercaseUuid()`](#generateShortLowercaseUuid)                                 | 20     | `15amp61jbnu6dzmhxa0i`                 |
 | [`generateLongLowercaseUuid()`](#generateLongLowercaseUuidshouldRemoveHyphens-boolean--false) | 36     | `e3703960-ca2d-4802-b426-88467e0e9b98` |
 | [`generateProfanitySafeUuid()`](#generateProfanitySafeUuid)                                   | 20     | `4a8g6z1w7d1a8d1o9o3o`                 |
@@ -89,10 +89,10 @@ Use this identifier when you need a strong but very short universally unique ide
 Generates a short cryptographically-strong random UUID using numbers and letters.\
 Use this identifier when you need a very strong but still compact universally unique id.
 
-* **Length:** 22
+* **Length:** 20
 * **Dictionary:** `0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`
-* **Example output:** `6ptGBhTKkxTMCMEiiHiwwj`
-* **Average UUIDs to be generated before having the first collision:** 6.52e+19
+* **Example output:** `6ptGBhTKkxTMCMEiiHiw`
+* **Average UUIDs to be generated before having the first collision:** 1.05e+18
 
 #### generateShortLowercaseUuid()
 

diff --git a/src/uuid-generator.ts b/src/uuid-generator.ts
@@ -32,16 +32,16 @@ export function generateShortUuid(): string {
 
 /**
  * Generates a short cryptographically-strong random UUID using numbers and letters.
- * Example: "6ptGBhTKkxTMCMEiiHiwwj".
+ * Example: "6ptGBhTKkxTMCMEiiHiw".
  * Use this identifier when you need a very strong but still compact universally unique id.
  *
- * Length of this UUID: 22 characters.
- * Total number of possible UUIDs: 62^22 = 2.70e+39, precisely 2'707'803'647'802'660'400'290'261'537'185'326'956'544
- * Probability of creating a duplicate ID when creating one billion (10^9, giga-unit) UUIDs: k^2÷2N = ((10^9)^2)÷(2*(62^22)) = 0.0000000000000000000185% (https://preshing.com/20110504/hash-collision-probabilities/)
- * Average UUIDs to be generated before having the first collision: sqrt(pi*0.5*62^22) = 6.52e+19 (https://shortunique.id/classes/default.html#approxmaxbeforecollision)
+ * Length of this UUID: 20 characters.
+ * Total number of possible UUIDs: 62^20 = 7.04e+35, precisely 704'423'425'546'998'022'968'330'264'616'370'176
+ * Probability of creating a duplicate ID when creating one billion (10^9, giga-unit) UUIDs: k^2÷2N = ((10^9)^2)÷(2*(62^20)) = 0.000000000000000071% (https://preshing.com/20110504/hash-collision-probabilities/)
+ * Average UUIDs to be generated before having the first collision: sqrt(pi*0.5*62^20) = 1.05e+18 (https://shortunique.id/classes/default.html#approxmaxbeforecollision)
  */
 export function generateStrongCompactUuid(): string {
-  return generateCustomUuid("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", 22);
+  return generateCustomUuid("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", 20);
 }
 
 /**

diff --git a/test/uuid-generator.test.ts b/test/uuid-generator.test.ts
@@ -96,7 +96,7 @@ describe('uuidGenerator', function() {
     for (let i = 0; i < DEFAULT_NUMBER_OF_TEST_SAMPLES; i++) {
       const uuid = uuidGenerator.generateStrongCompactUuid();
       expect(uuid).to.be.a("string");
-      assert.equal(uuid.length, 22);
+      assert.equal(uuid.length, 20);
       expect(doesStringContainOnlySimpleCharacters(uuid)).to.be.true;
       listOfUuids.push(uuid);
     }