jQuery.deparam: coerce standalone keys to null values

jquery.ba-bbq.js

@@ -451,19 +451,22 @@
   // 
   // Usage:
   // 
-  // > jQuery.deparam( params [, coerce ] );
+  // > jQuery.deparam( params [, coerce, standaloneKeys ] );
   // 
   // Arguments:
   // 
   //  params - (String) A params string to be parsed.
   //  coerce - (Boolean) If true, coerces any numbers or true, false, null, and
   //    undefined to their actual value. Defaults to false if omitted.
+  //  standaloneKeys - (Boolean) If true, keys without values are allowed in
+  //    the input string, and will be returned as null.  Defaults to false if
+  //    omitted.
   // 
   // Returns:
   // 
   //  (Object) An object representing the deserialized params string.
 
-  $.deparam = jq_deparam = function( params, coerce ) {
+  $.deparam = jq_deparam = function( params, coerce, standaloneKeys ) {
     var obj = {},
       coerce_types = { 'true': !0, 'false': !1, 'null': null };
 
@@ -507,48 +510,59 @@
             : coerce_types[val] !== undefined ? coerce_types[val] // true, false, null
             : val;                                                // string
         }
-
-        if ( keys_last ) {
-          // Complex key, build deep object structure based on a few rules:
-          // * The 'cur' pointer starts at the object top-level.
-          // * [] = array push (n is set to array length), [n] = array if n is 
-          //   numeric, otherwise object.
-          // * If at the last keys part, set the value.
-          // * For each keys part, if the current level is undefined create an
-          //   object or array based on the type of the next keys part.
-          // * Move the 'cur' pointer to the next level.
-          // * Rinse & repeat.
-          for ( ; i <= keys_last; i++ ) {
-            key = keys[i] === '' ? cur.length : keys[i];
-            cur = cur[key] = i < keys_last
-              ? cur[key] || ( keys[i+1] && isNaN( keys[i+1] ) ? {} : [] )
-              : val;
-          }
-
-        } else {
-          // Simple key, even simpler rules, since only scalars and shallow
-          // arrays are allowed.
-
-          if ( $.isArray( obj[key] ) ) {
-            // val is already an array, so push on the next value.
-            obj[key].push( val );
-
-          } else if ( obj[key] !== undefined ) {
-            // val isn't an array, but since a second value has been specified,
-            // convert val into an array.
-            obj[key] = [ obj[key], val ];
-
-          } else {
-            // val is a scalar.
-            obj[key] = val;
-          }
-        }
-
-      } else if ( key ) {
+      }
+
+      else if ( param.length === 1 && key ) {
         // No value was defined, so set something meaningful.
-        obj[key] = coerce
-          ? undefined
+        val = coerce
+          ? standaloneKeys
+            ? null
+            : undefined
           : '';
+
+        if (!standaloneKeys) {
+          // Backwards-compatibility:
+          // * Prior to the introduction of the standaloneKeys parameter, keys
+          //   without corresponding values would result in an undefined entry
+          keys_last = false;
+          obj[key] = undefined;
+        }
+      }
+
+      if ( keys_last ) {
+        // Complex key, build deep object structure based on a few rules:
+        // * The 'cur' pointer starts at the object top-level.
+        // * [] = array push (n is set to array length), [n] = array if n is
+        //   numeric, otherwise object.
+        // * If at the last keys part, set the value.
+        // * For each keys part, if the current level is undefined create an
+        //   object or array based on the type of the next keys part.
+        // * Move the 'cur' pointer to the next level.
+        // * Rinse & repeat.
+        for ( ; i <= keys_last; i++ ) {
+          key = keys[i] === '' ? cur.length : keys[i];
+          cur = cur[key] = i < keys_last
+            ? cur[key] || ( keys[i+1] && isNaN( keys[i+1] ) ? {} : [] )
+            : val;
+        }
+
+      } else if ( key ) {
+        // Simple key, even simpler rules, since only scalars and shallow
+        // arrays are allowed.
+
+        if ( $.isArray( obj[key] ) ) {
+          // val is already an array, so push on the next value.
+          obj[key].push( val );
+
+        } else if ( obj[key] !== undefined ) {
+          // val isn't an array, but since a second value has been specified,
+          // convert val into an array.
+          obj[key] = [ obj[key], val ];
+
+        } else {
+          // val is a scalar.
+          obj[key] = val;
+        }
       }
     });
 

unit/unit.js

@@ -478,6 +478,24 @@ test( 'jQuery.deparam - pre-1.4-style params', function() {
   same( $.deparam( params_str, true ), params_obj_coerce, '$.deparam( String, true )' );
 });
 
+test( 'jQuery.deparam - standalone keys', function() {
+  var params_str = 'a=1&a&b=2&c=3&c=undefined&c=&d&e[a]=4&e[b]&e[c]=';
+
+  // Backwards-compatibility test cases
+  var bc_params_obj = { a:'', b:'2', c:['3','undefined',''], d:'', e:{a:'4',c:''}, 'e[b]':'' },
+      bc_params_obj_coerce = { a:undefined, b:2, c:[3,undefined,''], d:undefined, e:{a:4,c:''}, 'e[b]':undefined };
+
+  // Intended-behaviour test cases
+  var params_obj = { a:['1',''], b:'2', c:['3','undefined',''], d:'', e:{a:'4',b:'',c:''} },
+      params_obj_coerce = { a:[1,null], b:2, c:[3,undefined,''], d:null, e:{a:4,b:null,c:''} };
+
+  expect( 4 );
+  same( $.deparam( params_str, false ), bc_params_obj, '$.deparam( String, false )' );
+  same( $.deparam( params_str, true ), bc_params_obj_coerce, '$.deparam( String, true )' );
+  same( $.deparam( params_str, false, true ), params_obj, '$.deparam( String, false, true )' );
+  same( $.deparam( params_str, true, true ), params_obj_coerce, '$.deparam( String, true, true )' );
+});
+
 test( 'jQuery.deparam.querystring', function() {
   expect( 12 );