feat: b64toURLSafe() convert base64 string to URL-safe string

https://en.wikipedia.org/wiki/Base64#URL_applications

Author: waitingsong

src/index.ts

@@ -3,6 +3,7 @@ export * from './lib/index'
 export * from './lib/model'
 export { ErrorMsg } from './lib/config'
 export {
+  b64toURLSafe,
   isArrayBuffer,
   isUint8Array,
   testB64,

src/lib/helper.ts

@@ -144,3 +144,18 @@ export function isUint8Array(buffer: any): buffer is Uint8Array {
     ? true
     : false
 }
+
+
+/**
+ * Convert base64 string to URL-safe string.
+ * Replace "+" to "-" and "/" to "_", and Remove "="
+ *
+ * @see https://en.wikipedia.org/wiki/Base64#URL_applications
+ */
+export function b64toURLSafe(base64: string): string {
+  validateB64(base64)
+  const pos = base64.indexOf('=')
+  return pos > 0
+    ? base64.slice(0, pos).replace(/\+/g, '-').replace(/\//g, '_')
+    : base64.replace(/\+/g, '-').replace(/\//g, '_')
+}

test/30_helper.test.ts

@@ -13,6 +13,7 @@ import {
 
 import { ErrorMsg } from '../src/index'
 import {
+  b64toURLSafe,
   isArrayBuffer,
   isUint8Array,
   parseDecodeInputBase64,
@@ -334,4 +335,27 @@ describe(filename, () => {
   })
 
 
+  describe('base64ToURLSafe() works', () => {
+    it('with valid input', () => {
+      inputURLSafe.forEach(([str, b64, b64url]) => {
+        const ret = b64toURLSafe(b64)
+        const b64node = Buffer.from(str).toString('base64')
+        assert(ret === b64url, `"${ret}" !== "${b64url}"`)
+        assert(b64 === b64node, `${b64} !== ${b64node}`)
+      })
+    })
+
+    it('with invalid input', () => {
+      inputURLSafe2.forEach(b64 => {
+        try {
+          b64toURLSafe(b64)
+          assert(false, 'Should throw error, but NOT')
+        }
+        catch (ex) {
+          assert(true)
+        }
+      })
+    })
+  })
+
 })

test/config.ts

@@ -155,7 +155,11 @@ export const inputURLSafe = [
 ]
 
 export const inputURLSafe2 = [
-  'A', 'QQ', '=QQ', 'Q=Q',
+  'A',
+  'QQ',
+  '=QQ',
+  'Q=Q',
+  'AABB\nAABB',
 ]
 
 export const inputBase64CharsInvalid = [
@@ -166,6 +170,7 @@ export const inputBase64CharsInvalid = [
   '=QQ==',
   '=QQ=',
   '=QQ',
+  'AABB\nAABB',
 ]
 export const inputBase64Invalid = [
   0,
@@ -180,6 +185,7 @@ export const inputBase64Invalid = [
   '=QQ==',
   '=QQ=',
   '=QQ',
+  'AABB\nAABB',
 ]
 
 export const inputBase64URLCharsInvalid = [
@@ -191,9 +197,11 @@ export const inputBase64URLCharsInvalid = [
   '=QQ==',
   '=QQ',
   'QQ+/',
+  'AABB\nAABB',
 ]
 export const inputBase64URLInvalid = [
   0,
   '',
   'Q',
+  'AABB\nAABB',
 ]