perf(fetch): Improve fetch of detaurl

lib/fetch/dataURL.js

@@ -1,5 +1,4 @@
 const assert = require('assert')
-const { atob } = require('buffer')
 const { isomorphicDecode } = require('./util')
 
 const encoder = new TextEncoder()
@@ -8,7 +7,8 @@ const encoder = new TextEncoder()
  * @see https://mimesniff.spec.whatwg.org/#http-token-code-point
  */
 const HTTP_TOKEN_CODEPOINTS = /^[!#$%&'*+-.^_|~A-Za-z0-9]+$/
-const HTTP_WHITESPACE_REGEX = /(\u000A|\u000D|\u0009|\u0020)/ // eslint-disable-line
+const HTTP_WHITESPACE_REGEX = /[\u000A|\u000D|\u0009|\u0020]/ // eslint-disable-line
+const ASCII_WHITESPACE_REPLACE_REGEX = /[\u0009\u000A\u000C\u000D\u0020]/g // eslint-disable-line
 /**
  * @see https://mimesniff.spec.whatwg.org/#http-quoted-string-token-code-point
  */
@@ -26,7 +26,7 @@ function dataURLProcessor (dataURL) {
   let input = URLSerializer(dataURL, true)
 
   // 3. Remove the leading "data:" string from input.
-  input = input.slice(5)
+  input = input.substring(5)
 
   // 4. Let position point at the start of input.
   const position = { position: 0 }
@@ -59,7 +59,7 @@ function dataURLProcessor (dataURL) {
   position.position++
 
   // 9. Let encodedBody be the remainder of input.
-  const encodedBody = input.slice(mimeTypeLength + 1)
+  const encodedBody = input.substring(mimeTypeLength + 1)
 
   // 10. Let body be the percent-decoding of encodedBody.
   let body = stringPercentDecode(encodedBody)
@@ -165,11 +165,11 @@ function collectASequenceOfCodePointsFast (char, input, position) {
 
   if (idx === -1) {
     position.position = input.length
-    return input.slice(start)
+    return input.substring(start)
   }
 
   position.position = idx
-  return input.slice(start, position.position)
+  return input.substring(start, position.position)
 }
 
 // https://url.spec.whatwg.org/#string-percent-decode
@@ -182,20 +182,25 @@ function stringPercentDecode (input) {
   return percentDecode(bytes)
 }
 
+function isHexCharByte (byte) {
+  return (byte >= 0x30 && byte <= 0x39) || (byte >= 0x41 && byte <= 0x46) || (byte >= 0x61 && byte <= 0x66)
+}
+
 // https://url.spec.whatwg.org/#percent-decode
 /** @param {Uint8Array} input */
 function percentDecode (input) {
   // 1. Let output be an empty byte sequence.
-  /** @type {number[]} */
-  const output = []
-
+  const length = input.length
+  /** @type {Uint8Array} */
+  const output = new Uint8Array(length)
+  let j = 0
   // 2. For each byte byte in input:
-  for (let i = 0; i < input.length; i++) {
+  for (let i = 0; i < length; ++i) {
     const byte = input[i]
 
     // 1. If byte is not 0x25 (%), then append byte to output.
     if (byte !== 0x25) {
-      output.push(byte)
+      output[j++] = byte
 
     // 2. Otherwise, if byte is 0x25 (%) and the next two bytes
     // after byte in input are not in the ranges
@@ -204,9 +209,9 @@ function percentDecode (input) {
     // to output.
     } else if (
       byte === 0x25 &&
-      !/^[0-9A-Fa-f]{2}$/i.test(String.fromCharCode(input[i + 1], input[i + 2]))
+      !(isHexCharByte(input[i + 1]) && isHexCharByte(input[i + 2]))
     ) {
-      output.push(0x25)
+      output[j++] = 0x25
 
     // 3. Otherwise:
     } else {
@@ -216,15 +221,15 @@ function percentDecode (input) {
       const bytePoint = Number.parseInt(nextTwoBytes, 16)
 
       // 2. Append a byte whose value is bytePoint to output.
-      output.push(bytePoint)
+      output[j++] = bytePoint
 
       // 3. Skip the next two bytes in input.
       i += 2
     }
   }
 
   // 3. Return output.
-  return Uint8Array.from(output)
+  return length === j ? output : output.subarray(0, j)
 }
 
 // https://mimesniff.spec.whatwg.org/#parse-a-mime-type
@@ -404,7 +409,7 @@ function parseMIMEType (input) {
 /** @param {string} data */
 function forgivingBase64 (data) {
   // 1. Remove all ASCII whitespace from data.
-  data = data.replace(/[\u0009\u000A\u000C\u000D\u0020]/g, '')  // eslint-disable-line
+  data = data.replace(ASCII_WHITESPACE_REPLACE_REGEX, '')  // eslint-disable-line
 
   // 2. If data’s code point length divides by 4 leaving
   // no remainder, then:
@@ -429,14 +434,8 @@ function forgivingBase64 (data) {
     return 'failure'
   }
 
-  const binary = atob(data)
-  const bytes = new Uint8Array(binary.length)
-
-  for (let byte = 0; byte < binary.length; byte++) {
-    bytes[byte] = binary.charCodeAt(byte)
-  }
-
-  return bytes
+  const buffer = Buffer.from(data, 'base64')
+  return new Uint8Array(buffer.buffer, buffer.byteOffset, buffer.byteLength)
 }
 
 // https://fetch.spec.whatwg.org/#collect-an-http-quoted-string
@@ -515,7 +514,7 @@ function collectAnHTTPQuotedString (input, position, extractValue) {
 
   // 7. Return the code points from positionStart to position,
   // inclusive, within input.
-  return input.slice(positionStart, position.position)
+  return input.substring(positionStart, position.position)
 }
 
 /**
@@ -564,55 +563,54 @@ function serializeAMimeType (mimeType) {
 
 /**
  * @see https://fetch.spec.whatwg.org/#http-whitespace
- * @param {string} char
+ * @param {number} char
  */
 function isHTTPWhiteSpace (char) {
-  return char === '\r' || char === '\n' || char === '\t' || char === ' '
+  // "\r\n\t "
+  return char === 0x00d || char === 0x00a || char === 0x009 || char === 0x020
 }
 
 /**
  * @see https://fetch.spec.whatwg.org/#http-whitespace
  * @param {string} str
+ * @param {boolean} [leading=true]
+ * @param {boolean} [trailing=true]
  */
 function removeHTTPWhitespace (str, leading = true, trailing = true) {
-  let lead = 0
-  let trail = str.length - 1
-
+  let i = 0; let j = str.length
   if (leading) {
-    for (; lead < str.length && isHTTPWhiteSpace(str[lead]); lead++);
+    while (j > i && isHTTPWhiteSpace(str.charCodeAt(i))) --i
   }
-
   if (trailing) {
-    for (; trail > 0 && isHTTPWhiteSpace(str[trail]); trail--);
+    while (j > i && isHTTPWhiteSpace(str.charCodeAt(j - 1))) --j
   }
-
-  return str.slice(lead, trail + 1)
+  return i === 0 && j === str.length ? str : str.substring(i, j)
 }
 
 /**
  * @see https://infra.spec.whatwg.org/#ascii-whitespace
- * @param {string} char
+ * @param {number} char
  */
 function isASCIIWhitespace (char) {
-  return char === '\r' || char === '\n' || char === '\t' || char === '\f' || char === ' '
+  // "\r\n\t\f "
+  return char === 0x00d || char === 0x00a || char === 0x009 || char === 0x00c || char === 0x020
 }
 
 /**
  * @see https://infra.spec.whatwg.org/#strip-leading-and-trailing-ascii-whitespace
+ * @param {string} str
+ * @param {boolean} [leading=true]
+ * @param {boolean} [trailing=true]
  */
 function removeASCIIWhitespace (str, leading = true, trailing = true) {
-  let lead = 0
-  let trail = str.length - 1
-
+  let i = 0; let j = str.length
   if (leading) {
-    for (; lead < str.length && isASCIIWhitespace(str[lead]); lead++);
+    while (j > i && isASCIIWhitespace(str.charCodeAt(i))) --i
   }
-
   if (trailing) {
-    for (; trail > 0 && isASCIIWhitespace(str[trail]); trail--);
+    while (j > i && isASCIIWhitespace(str.charCodeAt(j - 1))) --j
   }
-
-  return str.slice(lead, trail + 1)
+  return i === 0 && j === str.length ? str : str.substring(i, j)
 }
 
 module.exports = {

lib/fetch/util.js

@@ -904,8 +904,6 @@ function isReadableStreamLike (stream) {
   )
 }
 
-const MAXIMUM_ARGUMENT_LENGTH = 65535
-
 /**
  * @see https://infra.spec.whatwg.org/#isomorphic-decode
  * @param {number[]|Uint8Array} input
@@ -914,12 +912,36 @@ function isomorphicDecode (input) {
   // 1. To isomorphic decode a byte sequence input, return a string whose code point
   //    length is equal to input’s length and whose code points have the same values
   //    as the values of input’s bytes, in the same order.
-
-  if (input.length < MAXIMUM_ARGUMENT_LENGTH) {
-    return String.fromCharCode(...input)
+  const length = input.length
+  if ((2 << 15) - 1 > length) {
+    return String.fromCharCode.apply(null, input)
   }
-
-  return input.reduce((previous, current) => previous + String.fromCharCode(current), '')
+  let result = ''; let i = 0
+  if ('buffer' in input) {
+    let addition = (2 << 15) - 1
+    while (i < length) {
+      if (i + addition > length) {
+        addition = length - i
+      }
+      result += String.fromCharCode.apply(null, input.subarray(i, i += addition))
+    }
+    return result
+  }
+  // FIXME: Is there really a case here?
+  while (i + 32 < length) {
+    result += String.fromCharCode(
+      input[i], input[i + 1], input[i + 2], input[i + 3], input[i + 4], input[i + 5], input[i + 6], input[i + 7],
+      input[i + 8], input[i + 9], input[i + 10], input[i + 11], input[i + 12], input[i + 13], input[i + 14], input[i + 15],
+      input[i + 16], input[i + 17], input[i + 18], input[i + 19], input[i + 20], input[i + 21], input[i + 22], input[i + 23],
+      input[i + 24], input[i + 25], input[i + 26], input[i + 27], input[i + 28], input[i + 29], input[i + 30], input[i + 31]
+    )
+    i += 32
+  }
+  // Decode the remaining characters.
+  while (i < length) {
+    result += String.fromCharCode(input[i++])
+  }
+  return result
 }
 
 /**