feat: accept pairs with missing values

Author: anonrig

README.md

@@ -16,10 +16,6 @@ npm i --save fast-querystring
 - Supports repeating keys in query string
   - `foo=bar&foo=baz` parses into `{foo: ['bar', 'baz']}`
 
-### Differences
-- Key & value with length 0 is omitted by default
-  - `foo=bar&hey` parses into `{foo: 'bar'}`, but `node:querystring` returns `{foo: 'bar', hey: ''}`
-
 ### Usage
 
 ```javascript

lib/parse.js

@@ -25,10 +25,19 @@ function parse(input) {
 
     // Handle '&' and end of line to pass the current values to result
     if (c === 38 || isNaN(c)) {
-      // Disallow empty key values.
-      if (equalityIndex - separatorIndex > 0 && i - equalityIndex + 1 > 0) {
-        key = input.slice(separatorIndex, equalityIndex);
-        value = input.slice(equalityIndex + 1, i);
+      const hasOnlyKey = equalityIndex <= separatorIndex;
+      const keySize =
+        hasOnlyKey ? i - separatorIndex : equalityIndex - separatorIndex;
+
+      if (keySize > 0) {
+        // Accept empty values, if key size is positive
+        if (hasOnlyKey) {
+          key = input.slice(separatorIndex, i);
+          value = "";
+        } else {
+          key = input.slice(separatorIndex, equalityIndex);
+          value = input.slice(equalityIndex + 1, i);
+        }
 
         // Optimization: Replace '+' with space
         if (hasPlus) {

test/basics.test.ts

@@ -45,3 +45,8 @@ test("handles + character", () => {
     author: "Yagiz Nizipli",
   });
 });
+
+test("should accept pairs with missing values", () => {
+  assert.deepEqual(qs.parse("foo=bar&hey"), { foo: "bar", hey: "" });
+  assert.deepEqual(qs.parse("hey"), { hey: "" });
+});