[New] qs.stringify: add encodeValuesOnly option

.eslintrc

@@ -4,12 +4,12 @@
     "extends": "@ljharb",
 
     "rules": {
-        "complexity": [2, 25],
+        "complexity": [2, 26],
         "consistent-return": 1,
         "id-length": [2, { "min": 1, "max": 25, "properties": "never" }],
         "indent": [2, 4],
-        "max-params": [2, 11],
-        "max-statements": [2, 42],
+        "max-params": [2, 12],
+        "max-statements": [2, 43],
         "no-extra-parens": 1,
         "no-continue": 1,
         "no-magic-numbers": 0,

README.md

@@ -225,6 +225,15 @@ var unencoded = qs.stringify({ a: { b: 'c' } }, { encode: false });
 assert.equal(unencoded, 'a[b]=c');
 ```
 
+Encoding can be disabled for keys by setting the `encodeValuesOnly` option to `true`:
+```javascript
+var encodedValues  = qs.stringify(
+  { a: 'b', c: ['d', 'e=f'], f: [['g'], ['h']] },
+  { encodeValuesOnly: true }
+)
+assert.equal(encodedValues,'a=b&c[0]=d&c[1]=e%3Df&f[0][0]=g&f[1][0]=h');
+```
+
 This encoding can also be replaced by a custom encoding method set as `encoder` option:
 
 ```javascript
@@ -400,7 +409,7 @@ assert.equal(nullsSkipped, 'a=b');
 
 ### Dealing with special character sets
 
-By default the encoding and decoding of characters is done in `utf-8`. If you 
+By default the encoding and decoding of characters is done in `utf-8`. If you
 wish to encode querystrings to a different character set (i.e.
 [Shift JIS](https://en.wikipedia.org/wiki/Shift_JIS)) you can use the
 [`qs-iconv`](https://github.com/martinheidegger/qs-iconv) library:

lib/stringify.js

@@ -21,6 +21,7 @@ var defaults = {
     delimiter: '&',
     encode: true,
     encoder: utils.encode,
+    encodeValuesOnly: false,
     serializeDate: function serializeDate(date) { // eslint-disable-line func-name-matching
         return toISO.call(date);
     },
@@ -39,7 +40,8 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
     sort,
     allowDots,
     serializeDate,
-    formatter
+    formatter,
+    encodeValuesOnly
 ) {
     var obj = object;
     if (typeof filter === 'function') {
@@ -48,15 +50,16 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
         obj = serializeDate(obj);
     } else if (obj === null) {
         if (strictNullHandling) {
-            return encoder ? encoder(prefix) : prefix;
+            return encoder && !encodeValuesOnly ? encoder(prefix) : prefix;
         }
 
         obj = '';
     }
 
     if (typeof obj === 'string' || typeof obj === 'number' || typeof obj === 'boolean' || utils.isBuffer(obj)) {
         if (encoder) {
-            return [formatter(encoder(prefix)) + '=' + formatter(encoder(obj))];
+            var keyValue = encodeValuesOnly ? prefix : encoder(prefix);
+            return [formatter(keyValue) + '=' + formatter(encoder(obj))];
         }
         return [formatter(prefix) + '=' + formatter(String(obj))];
     }
@@ -94,7 +97,8 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
                 sort,
                 allowDots,
                 serializeDate,
-                formatter
+                formatter,
+                encodeValuesOnly
             ));
         } else {
             values = values.concat(stringify(
@@ -108,7 +112,8 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
                 sort,
                 allowDots,
                 serializeDate,
-                formatter
+                formatter,
+                encodeValuesOnly
             ));
         }
     }
@@ -132,6 +137,7 @@ module.exports = function (object, opts) {
     var sort = typeof options.sort === 'function' ? options.sort : null;
     var allowDots = typeof options.allowDots === 'undefined' ? false : options.allowDots;
     var serializeDate = typeof options.serializeDate === 'function' ? options.serializeDate : defaults.serializeDate;
+    var encodeValuesOnly = typeof options.encodeValuesOnly === 'boolean' ? options.encodeValuesOnly : defaults.encodeValuesOnly;
     if (typeof options.format === 'undefined') {
         options.format = formats.default;
     } else if (!Object.prototype.hasOwnProperty.call(formats.formatters, options.format)) {
@@ -192,7 +198,8 @@ module.exports = function (object, opts) {
             sort,
             allowDots,
             serializeDate,
-            formatter
+            formatter,
+            encodeValuesOnly
         ));
     }
 

test/stringify.js

@@ -535,4 +535,33 @@ test('stringify()', function (t) {
         );
         st.end();
     });
+
+    t.test('encodeValuesOnly', function (st) {
+        st.equal(
+            qs.stringify(
+                { a: 'b', c: ['d', 'e=f'], f: [['g'], ['h']] },
+                { encodeValuesOnly: true }
+            ),
+            'a=b&c[0]=d&c[1]=e%3Df&f[0][0]=g&f[1][0]=h'
+        );
+        st.equal(
+            qs.stringify(
+                { a: 'b', c: ['d', 'e'], f: [['g'], ['h']] }
+            ),
+            'a=b&c%5B0%5D=d&c%5B1%5D=e&f%5B0%5D%5B0%5D=g&f%5B1%5D%5B0%5D=h'
+        );
+        st.end();
+    });
+
+    t.test('encodeValuesOnly - strictNullHandling', function (st) {
+        st.equal(
+            qs.stringify(
+                { a: { b: null } },
+                { encodeValuesOnly: true, strictNullHandling: true }
+            ),
+            'a[b]'
+        );
+        st.end();
+    });
+
 });