[New] Prefix option for parse function

.eslintrc

@@ -4,12 +4,12 @@
     "extends": "@ljharb",
 
     "rules": {
-        "complexity": [2, 26],
+        "complexity": [2, 27],
         "consistent-return": 1,
         "id-length": [2, { "min": 1, "max": 25, "properties": "never" }],
         "indent": [2, 4],
         "max-params": [2, 12],
-        "max-statements": [2, 43],
+        "max-statements": [2, 44],
         "no-continue": 1,
         "no-magic-numbers": 0,
         "no-restricted-syntax": [2, "BreakStatement", "DebuggerStatement", "ForInStatement", "LabeledStatement", "WithStatement"],

README.md

@@ -118,6 +118,13 @@ var limited = qs.parse('a=b&c=d', { parameterLimit: 1 });
 assert.deepEqual(limited, { a: 'b' });
 ```
 
+To bypass the leading question mark, use `ignoreQueryPrefix`:
+
+```javascript
+var prefixed = qs.parse('?a=b&c=d', { ignoreQueryPrefix: true });
+assert.deepEqual(prefixed, { a: 'b', c: 'd' });
+```
+
 An optional delimiter can also be passed:
 
 ```javascript
@@ -323,6 +330,12 @@ Properties that are set to `undefined` will be omitted entirely:
 assert.equal(qs.stringify({ a: null, b: undefined }), 'a=');
 ```
 
+The query string may optionally be prepended with a question mark:
+
+```javascript
+assert.equal(qs.stringify({ a: 'b', c: 'd' }, { addQueryPrefix: true }), '?a=b&c=d');
+```
+
 The delimiter may be overridden with stringify as well:
 
 ```javascript

lib/parse.js

@@ -18,7 +18,9 @@ var defaults = {
 
 var parseValues = function parseQueryStringValues(str, options) {
     var obj = {};
-    var parts = str.split(options.delimiter, options.parameterLimit === Infinity ? undefined : options.parameterLimit);
+    var cleanStr = options.ignoreQueryPrefix ? str.replace(/^\?/, '') : str;
+    var limit = options.parameterLimit === Infinity ? undefined : options.parameterLimit;
+    var parts = cleanStr.split(options.delimiter, limit);
 
     for (var i = 0; i < parts.length; ++i) {
         var part = parts[i];
@@ -136,6 +138,7 @@ module.exports = function (str, opts) {
         throw new TypeError('Decoder has to be a function.');
     }
 
+    options.ignoreQueryPrefix = options.ignoreQueryPrefix === true;
     options.delimiter = typeof options.delimiter === 'string' || utils.isRegExp(options.delimiter) ? options.delimiter : defaults.delimiter;
     options.depth = typeof options.depth === 'number' ? options.depth : defaults.depth;
     options.arrayLimit = typeof options.arrayLimit === 'number' ? options.arrayLimit : defaults.arrayLimit;

lib/stringify.js

@@ -203,5 +203,7 @@ module.exports = function (object, opts) {
         ));
     }
 
-    return keys.join(delimiter);
+    var prefix = options.addQueryPrefix === true ? '?' : '';
+
+    return prefix + keys.join(delimiter);
 };

test/parse.js

@@ -305,6 +305,13 @@ test('parse()', function (t) {
         st.end();
     });
 
+    t.test('allows for query string prefix', function (st) {
+        st.deepEqual(qs.parse('?foo=bar', { ignoreQueryPrefix: true }), { foo: 'bar' });
+        st.deepEqual(qs.parse('foo=bar', { ignoreQueryPrefix: true }), { foo: 'bar' });
+        st.deepEqual(qs.parse('?foo=bar', { ignoreQueryPrefix: false }), { '?foo': 'bar' });
+        st.end();
+    });
+
     t.test('parses an object', function (st) {
         var input = {
             'user[name]': { 'pop[bob]': 3 },

test/stringify.js

@@ -18,6 +18,11 @@ test('stringify()', function (t) {
         st.end();
     });
 
+    t.test('adds query prefix', function (st) {
+        st.equal(qs.stringify({ a: 'b' }, { addQueryPrefix: true }), '?a=b');
+        st.end();
+    });
+
     t.test('stringifies a nested object', function (st) {
         st.equal(qs.stringify({ a: { b: 'c' } }), 'a%5Bb%5D=c');
         st.equal(qs.stringify({ a: { b: { c: { d: 'e' } } } }), 'a%5Bb%5D%5Bc%5D%5Bd%5D=e');