Optimize base64Write, remove base64-js dependency

Also adds support for `base64url` encoding.

Author: chjj

index.js

@@ -8,7 +8,6 @@
 
 'use strict'
 
-const base64 = require('base64-js')
 const ieee754 = require('ieee754')
 const customInspectSymbol =
   (typeof Symbol === 'function' && typeof Symbol['for'] === 'function') // eslint-disable-line dot-notation
@@ -393,6 +392,7 @@ Buffer.isEncoding = function isEncoding (encoding) {
     case 'latin1':
     case 'binary':
     case 'base64':
+    case 'base64url':
     case 'ucs2':
     case 'ucs-2':
     case 'utf16le':
@@ -484,7 +484,8 @@ function byteLength (string, encoding) {
       case 'hex':
         return len >>> 1
       case 'base64':
-        return base64ToBytes(string).length
+      case 'base64url':
+        return base64ByteLength(string, len)
       default:
         if (loweredCase) {
           return mustMatch ? -1 : utf8ByteLength(string) // assume utf8
@@ -550,7 +551,10 @@ function slowToString (encoding, start, end) {
         return latin1Slice(this, start, end)
 
       case 'base64':
-        return base64Slice(this, start, end)
+        return base64Slice(this, start, end, base64Charset, true)
+
+      case 'base64url':
+        return base64Slice(this, start, end, base64UrlCharset, false)
 
       case 'ucs2':
       case 'ucs-2':
@@ -1015,7 +1019,62 @@ function asciiWrite (buf, string, offset, length) {
 }
 
 function base64Write (buf, string, offset, length) {
-  return blitBuffer(base64ToBytes(string), buf, offset, length)
+  const src = string.replace(/[^+/0-9A-Za-z-_=]/g, '')
+  const eq = src.indexOf('=')
+  const dst = buf
+
+  let srcLen = eq >= 0 ? eq : src.length
+  let srcPos = 0
+  let dstLen = length
+  let dstPos = offset
+
+  while (srcLen >= 4 && dstLen >= 3) {
+    const t1 = base64Table[src.charCodeAt(srcPos++)]
+    const t2 = base64Table[src.charCodeAt(srcPos++)]
+    const t3 = base64Table[src.charCodeAt(srcPos++)]
+    const t4 = base64Table[src.charCodeAt(srcPos++)]
+
+    dst[dstPos++] = (t1 << 2) | (t2 >> 4)
+    dst[dstPos++] = (t2 << 4) | (t3 >> 2)
+    dst[dstPos++] = (t3 << 6) | (t4 >> 0)
+
+    srcLen -= 4
+    dstLen -= 3
+  }
+
+  {
+    let w1, w2, w3, w4
+
+    while (srcLen && dstLen) {
+      const w = base64Table[src.charCodeAt(srcPos)]
+
+      switch (srcPos & 3) {
+        case 0:
+          w1 = w
+          break
+        case 1:
+          w2 = w
+          dst[dstPos++] = (w1 << 2) | (w2 >> 4)
+          dstLen--
+          break
+        case 2:
+          w3 = w
+          dst[dstPos++] = (w2 << 4) | (w3 >> 2)
+          dstLen--
+          break
+        case 3:
+          w4 = w
+          dst[dstPos++] = (w3 << 6) | (w4 >> 0)
+          dstLen--
+          break
+      }
+
+      srcPos++
+      srcLen--
+    }
+  }
+
+  return dstPos - offset
 }
 
 function ucs2Write (buf, string, offset, length) {
@@ -1091,6 +1150,7 @@ Buffer.prototype.write = function write (string, offset, length, encoding) {
         return asciiWrite(this, string, offset, length)
 
       case 'base64':
+      case 'base64url':
         // Warning: maxLength not taken into account in base64Write
         return base64Write(this, string, offset, length)
 
@@ -1115,12 +1175,53 @@ Buffer.prototype.toJSON = function toJSON () {
   }
 }
 
-function base64Slice (buf, start, end) {
-  if (start === 0 && end === buf.length) {
-    return base64.fromByteArray(buf)
-  } else {
-    return base64.fromByteArray(buf.slice(start, end))
+function base64Slice (buf, start, end, charset, pad) {
+  end = Math.min(buf.length, end)
+
+  let left = end - start
+  let i = start
+  let str = ''
+
+  while (left >= 3) {
+    const c1 = buf[i++]
+    const c2 = buf[i++]
+    const c3 = buf[i++]
+
+    str += charset[c1 >> 2]
+    str += charset[((c1 & 3) << 4) | (c2 >> 4)]
+    str += charset[((c2 & 15) << 2) | (c3 >> 6)]
+    str += charset[c3 & 63]
+
+    left -= 3
+  }
+
+  switch (left) {
+    case 1: {
+      const c1 = buf[i++]
+
+      str += charset[c1 >> 2]
+      str += charset[(c1 & 3) << 4]
+
+      if (pad) str += '=='
+
+      break
+    }
+
+    case 2: {
+      const c1 = buf[i++]
+      const c2 = buf[i++]
+
+      str += charset[c1 >> 2]
+      str += charset[((c1 & 3) << 4) | (c2 >> 4)]
+      str += charset[(c2 & 15) << 2]
+
+      if (pad) str += '='
+
+      break
+    }
   }
+
+  return str
 }
 
 function utf8Slice (buf, start, end) {
@@ -2109,26 +2210,6 @@ function boundsError (value, length, type) {
 // HELPER FUNCTIONS
 // ================
 
-const INVALID_BASE64_RE = /[^+/0-9A-Za-z-_]/g
-
-function base64clean (str) {
-  // Node takes equal signs as end of the Base64 encoding
-  str = str.split('=')[0]
-  // Node strips out invalid characters like \n and \t from the string, base64-js does not
-  str = str.trim().replace(INVALID_BASE64_RE, '')
-  // Node converts strings with length < 2 to ''
-  if (str.length < 2) return ''
-  // Node allows for non-padded base64 strings (missing trailing ===), base64-js does not
-  while (str.length % 4 !== 0) {
-    str = str + '='
-  }
-  return str
-}
-
-function base64ToBytes (str) {
-  return base64.toByteArray(base64clean(str))
-}
-
 function writeInvalid (buf, pos) {
   // U+FFFD (Replacement Character)
   buf[pos++] = 0xef
@@ -2137,13 +2218,18 @@ function writeInvalid (buf, pos) {
   return pos
 }
 
-function blitBuffer (src, dst, offset, length) {
-  let i
-  for (i = 0; i < length; ++i) {
-    if ((i + offset >= dst.length) || (i >= src.length)) break
-    dst[i + offset] = src[i]
+function base64ByteLength (str, bytes) {
+  // Handle padding
+  if (bytes > 0 && str.charCodeAt(bytes - 1) === 0x3d) {
+    bytes--
+  }
+
+  if (bytes > 1 && str.charCodeAt(bytes - 1) === 0x3d) {
+    bytes--
   }
-  return i
+
+  // Base64 ratio: 3/4
+  return (bytes * 3) >>> 2
 }
 
 // ArrayBuffer or Uint8Array objects from other contexts (i.e. iframes) do not pass
@@ -2195,6 +2281,33 @@ const hexCharValueTable = [
 ]
 /* eslint-enable no-multi-spaces, indent */
 
+const base64Charset =
+  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+
+const base64UrlCharset =
+  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_'
+
+/* eslint-disable no-multi-spaces, indent */
+const base64Table = [
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, 62, -1, 62, -1, 63,
+  52, 53, 54, 55, 56, 57, 58, 59,
+  60, 61, -1, -1, -1, -1, -1, -1,
+  -1,  0,  1,  2,  3,  4,  5,  6,
+   7,  8,  9, 10, 11, 12, 13, 14,
+  15, 16, 17, 18, 19, 20, 21, 22,
+  23, 24, 25, -1, -1, -1, -1, 63,
+  -1, 26, 27, 28, 29, 30, 31, 32,
+  33, 34, 35, 36, 37, 38, 39, 40,
+  41, 42, 43, 44, 45, 46, 47, 48,
+  49, 50, 51, -1, -1, -1, -1, -1
+]
+/* eslint-enable no-multi-spaces, indent */
+
 // Return not function with Error if BigInt not supported
 function defineBigIntMethod (fn) {
   return typeof BigInt === 'undefined' ? BufferBigIntNotDefined : fn

package.json

@@ -16,7 +16,6 @@
     "James Halliday <mail@substack.net>"
   ],
   "dependencies": {
-    "base64-js": "^1.3.1",
     "ieee754": "^1.2.1"
   },
   "devDependencies": {