[#37] isCuid(id) validates cuids

README.md

@@ -43,6 +43,41 @@ const ids = [
 ];
 ```
 
+### Configuration
+
+```js
+import { init } from '@paralleldrive/cuid2';
+
+// The init function returns a custom createId function with the specified
+// configuration.
+const createId = init({
+  // A custom random function with the same API as Math.random.
+  // You should use this to pass a cryptographically secure random function.
+  random: Math.random,
+  length: 10, // the length of the id
+  fingerprint: 'a-custom-host-fingerprint',
+});
+
+console.log(
+  createId(), // wjfazn7qnd
+  createId(), // cerhuy9499
+  createId(), // itp2u4ozr4
+);
+```
+
+
+### Validation
+
+```js
+import { createId, isCuid } from '@paralleldrive/cuid2';
+
+
+console.log(
+  isCuid(createId()), // true
+  isCuid('not a cuid'), // false
+);
+```
+
 
 ## Trusted By
 

index.d.ts

@@ -10,6 +10,8 @@ declare namespace cuid2 {
     fingerprint?: string
   }): () => string
 
+  export function isCuid(id: string): boolean
+
   export function createId(): string
 }
 

index.js

@@ -1,5 +1,6 @@
-const { createId, init, getConstants } = require("./src/index");
+const { createId, init, getConstants, isCuid } = require("./src/index");
 
 module.exports.createId = createId;
 module.exports.init = init;
 module.exports.getConstants = getConstants;
+module.exports.isCuid = isCuid;

src/index-test.js

@@ -6,6 +6,7 @@ const {
   createCounter,
   bufToBigInt,
   createFingerprint,
+  isCuid,
 } = require("./index");
 
 const { info } = require("./test-utils.js");
@@ -136,3 +137,41 @@ describe("createFingerprint", async (assert) => {
     });
   }
 });
+
+describe("isCuid", async (assert) => {
+  {
+    const actual = isCuid(createId());
+    const expected = true;
+
+    assert({
+      given: "a valid cuid",
+      should: "return true",
+      actual,
+      expected,
+    });
+  }
+
+  {
+    const actual = isCuid(createId() + createId() + createId());
+    const expected = false;
+
+    assert({
+      given: "a cuid that is too long",
+      should: "return false",
+      actual,
+      expected,
+    });
+  }
+
+  {
+    const actual = isCuid("");
+    const expected = false;
+
+    assert({
+      given: "an empty string",
+      should: "return false",
+      actual,
+      expected,
+    });
+  }
+});

src/index.js

@@ -99,9 +99,28 @@ const init = ({
 
 const createId = init();
 
+const isCuid = (id, { minLength = 2, maxLength = bigLength } = {}) => {
+  const length = id.length;
+  const regex = /^[0-9a-z]+$/;
+
+  try {
+    if (
+      typeof id === "string" &&
+      length >= minLength &&
+      length <= maxLength &&
+      regex.test(id)
+    )
+      return true;
+  } finally {
+  }
+
+  return false;
+};
+
 module.exports.getConstants = () => ({ defaultLength, bigLength });
 module.exports.init = init;
 module.exports.createId = createId;
 module.exports.bufToBigInt = bufToBigInt;
 module.exports.createCounter = createCounter;
 module.exports.createFingerprint = createFingerprint;
+module.exports.isCuid = isCuid;