perf: improve parse performance by 12%

Author: anonrig

README.md

@@ -48,17 +48,17 @@ console.log(qs.stringify({ foo: ['bar', 'baz'] }))
 ╔═════════════════════════════════════════╤═════════╤═══════════════════╤═══════════╗
 ║ Slower tests                            │ Samples │            Result │ Tolerance ║
 ╟─────────────────────────────────────────┼─────────┼───────────────────┼───────────╢
-║ qs                                      │   10000 │  317841.53 op/sec │  ± 1.18 % ║
-║ query-string                            │   10000 │  341009.91 op/sec │  ± 1.06 % ║
-║ querystringify                          │    1000 │  451609.79 op/sec │  ± 0.61 % ║
-║ @aws-sdk/querystring-parser             │    1000 │  477241.09 op/sec │  ± 0.69 % ║
-║ URLSearchParams-with-Object.fromEntries │   10000 │  870095.07 op/sec │  ± 3.29 % ║
-║ URLSearchParams-with-construct          │   10000 │ 1232650.60 op/sec │  ± 2.95 % ║
-║ node:querystring                        │   10000 │ 1462802.04 op/sec │  ± 3.69 % ║
+║ qs                                      │   10000 │  290743.91 op/sec │  ± 1.87 % ║
+║ query-string                            │    1500 │  333025.25 op/sec │  ± 0.98 % ║
+║ querystringify                          │   10000 │  430382.40 op/sec │  ± 1.95 % ║
+║ @aws-sdk/querystring-parser             │    3000 │  452331.29 op/sec │  ± 0.87 % ║
+║ URLSearchParams-with-Object.fromEntries │    2000 │  862635.26 op/sec │  ± 0.87 % ║
+║ URLSearchParams-with-construct          │   10000 │ 1216331.19 op/sec │  ± 3.19 % ║
+║ node:querystring                        │   10000 │ 1453849.93 op/sec │  ± 4.50 % ║
 ╟─────────────────────────────────────────┼─────────┼───────────────────┼───────────╢
 ║ Fastest test                            │ Samples │            Result │ Tolerance ║
 ╟─────────────────────────────────────────┼─────────┼───────────────────┼───────────╢
-║ fast-querystring                        │   10000 │ 1809816.84 op/sec │  ± 3.19 % ║
+║ fast-querystring                        │   10000 │ 2047629.50 op/sec │  ± 3.72 % ║
 ╚═════════════════════════════════════════╧═════════╧═══════════════════╧═══════════╝
 ```
 

lib/parse.js

@@ -1,21 +1,23 @@
-"use strict";
-
 const fastDecode = require("fast-decode-uri-component");
 
 const plusRegex = /\+/g;
+const Empty = function () {};
+Empty.prototype = Object.create(null);
 
 /**
  * @callback parse
  * @param {string} input
  */
 function parse(input) {
-  const result = Object.create(null);
+  // Optimization: Use new Empty() instead of Object.create(null) for performance
+  // v8 has a better optimization for initializing functions compared to Object
+  const result = new Empty();
 
   if (typeof input !== "string") {
     return result;
   }
 
-  const inputLength = input.length;
+  let inputLength = input.length;
   let key = "";
   let value = "";
   let startingIndex = -1;
@@ -37,13 +39,8 @@ function parse(input) {
       keyEndingIndex = hasBothKeyValuePair ? equalityIndex : i;
       key = input.slice(startingIndex + 1, keyEndingIndex);
 
-      // Only update value if '=' exists in the current range
-      if (hasBothKeyValuePair) {
-        value = input.slice(equalityIndex + 1, i);
-      }
-
       // Add key/value pair only if the range size is greater than 1; a.k.a. contains at least "="
-      if (hasBothKeyValuePair || i - startingIndex > 1) {
+      if (hasBothKeyValuePair || key.length > 0) {
         // Optimization: Replace '+' with space
         if (keyHasPlus) {
           key = key.replace(plusRegex, " ");
@@ -55,6 +52,8 @@ function parse(input) {
         }
 
         if (hasBothKeyValuePair) {
+          value = input.slice(equalityIndex + 1, i);
+
           if (valueHasPlus) {
             value = value.replace(plusRegex, " ");
           }
@@ -63,12 +62,11 @@ function parse(input) {
             value = fastDecode(value) || value;
           }
         }
+        const currentValue = result[key];
 
-        if (result[key] === undefined) {
+        if (currentValue === undefined) {
           result[key] = value;
         } else {
-          const currentValue = result[key];
-
           // Optimization: value.pop is faster than Array.isArray(value)
           if (currentValue.pop) {
             currentValue.push(value);
@@ -86,31 +84,31 @@ function parse(input) {
       shouldDecodeValue = false;
       keyHasPlus = false;
       valueHasPlus = false;
-      hasBothKeyValuePair = false;
     }
     // Check '='
     else if (c === 61) {
+      if (equalityIndex <= startingIndex) {
+        equalityIndex = i;
+      }
       // If '=' character occurs again, we should decode the input.
-      if (equalityIndex > startingIndex) {
+      else {
         shouldDecodeValue = true;
-      } else {
-        equalityIndex = i;
       }
     }
     // Check '+', and remember to replace it with empty space.
     else if (c === 43) {
-      if (equalityIndex <= startingIndex) {
-        keyHasPlus = true;
-      } else {
+      if (equalityIndex > startingIndex) {
         valueHasPlus = true;
+      } else {
+        keyHasPlus = true;
       }
     }
     // Check '%' character for encoding
     else if (c === 37) {
-      if (equalityIndex <= startingIndex) {
-        shouldDecodeKey = true;
-      } else {
+      if (equalityIndex > startingIndex) {
         shouldDecodeValue = true;
+      } else {
+        shouldDecodeKey = true;
       }
     }
   }