querystring: rebalance the performance of unescape

benchmark/querystring/querystring-unescape.js

@@ -0,0 +1,27 @@
+'use strict';
+const common = require('../common.js');
+const querystring = require('querystring');
+
+const bench = common.createBenchmark(main, {
+  input: [
+    'there is nothing to unescape here',
+    'there+are+spaces+to+unescape+here',
+    'there%20are%20several%20spaces%20that%20need%20to%20be%20unescaped',
+    '%20%21%22%23%24%25%26%27%28%29%2A%2B%2C%2D%2E%2F%30%31%32%33%34%35%36%37',
+    'there%2Qare%0-fake%escaped values in%%%%this%9Hstring',
+    'there%2Qare%0-fake%escaped%20values in%%%%this%9Hstring',
+    '%%2a',
+    '%2sf%2a',
+    '%2%2af%2a',
+  ],
+  n: [10e6],
+  decodeSpaces: [1, 0],
+});
+
+function main({ input, n, decodeSpaces }) {
+  decodeSpaces = !!decodeSpaces;
+  bench.start();
+  for (let i = 0; i < n; i += 1)
+    querystring.unescape(input, decodeSpaces);
+  bench.end(n);
+}

lib/querystring.js

@@ -28,10 +28,15 @@ const {
   ArrayIsArray,
   Int8Array,
   MathAbs,
+  NumberParseInt,
   NumberIsFinite,
   ObjectKeys,
+  RegExpPrototypeExec,
   String,
+  StringFromCharCode,
   StringPrototypeCharCodeAt,
+  StringPrototypeIndexOf,
+  StringPrototypeReplace,
   StringPrototypeSlice,
   decodeURIComponent,
 } = primordials;
@@ -125,17 +130,40 @@ function unescapeBuffer(s, decodeSpaces) {
 
 /**
  * @param {string} s
- * @param {boolean} decodeSpaces
+ * @param {boolean} [decodeSpaces=false]
  * @returns {string}
  */
-function qsUnescape(s, decodeSpaces) {
-  try {
-    return decodeURIComponent(s);
-  } catch {
-    return QueryString.unescapeBuffer(s, decodeSpaces).toString();
+function qsUnescape(s, decodeSpaces = false) {
+  if (StringPrototypeIndexOf(s, '%') === -1) {
+    return s;
+  }
+
+  if (RegExpPrototypeExec(MALFORMED_URI_REGEX, s) !== null) {
+    if (decodeSpaces) {
+      return StringPrototypeReplace(s, decodeSpacesRegexp, decodeSpacesReplacer);
+    }
+    return StringPrototypeReplace(s, baseRegexp, baseReplacer);
+
   }
+  return decodeURIComponent(s);
+
 }
 
+const MALFORMED_URI_REGEX = /(?:%(?:[^0-9a-fA-F]|[0-9a-fA-F][^0-9a-fA-F]))/u;
+
+const baseRegexp = /(%[\da-fA-F]{2})/gu;
+
+function baseReplacer(match) {
+  return StringFromCharCode(NumberParseInt(match[1] + match[2], 16));
+}
+
+const decodeSpacesRegexp = /(%[\da-fA-F]{2}|[+])/gu;
+
+function decodeSpacesReplacer(match) {
+  return match === '+' ?
+    ' ' :
+    StringFromCharCode(NumberParseInt(match[1] + match[2], 16));
+}
 
 // These characters do not need escaping when generating query strings:
 // ! - . _ ~

test/parallel/test-querystring.js

@@ -170,10 +170,14 @@ const qsNoMungeTestCases = [
 const qsUnescapeTestCases = [
   ['there is nothing to unescape here',
    'there is nothing to unescape here'],
+  ['there+is+nothing+to+unescape+here',
+   'there+is+nothing+to+unescape+here'],
   ['there%20are%20several%20spaces%20that%20need%20to%20be%20unescaped',
    'there are several spaces that need to be unescaped'],
   ['there%2Qare%0-fake%escaped values in%%%%this%9Hstring',
    'there%2Qare%0-fake%escaped values in%%%%this%9Hstring'],
+  ['there%2Qare%0-fake%escaped%20values in%%%%this%9Hstring',
+   'there%2Qare%0-fake%escaped values in%%%%this%9Hstring'],
   ['%20%21%22%23%24%25%26%27%28%29%2A%2B%2C%2D%2E%2F%30%31%32%33%34%35%36%37',
    ' !"#$%&\'()*+,-./01234567'],
   ['%%2a', '%*'],