diff --git a/.vscode/launch.json b/.vscode/launch.json
index a8e11b0..b6a45ab 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -4,7 +4,6 @@
     // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
     "version": "0.2.0",
     "configurations": [
-
         {
             "type": "node",
             "request": "launch",
diff --git a/lib/xml2js.js b/lib/xml2js.js
index 4ce7cdf..11ead12 100644
--- a/lib/xml2js.js
+++ b/lib/xml2js.js
@@ -35,6 +35,16 @@ function validateOptions(userOptions) {
   helper.ensureKeyExists('name', options);
   helper.ensureKeyExists('elements', options);
   helper.ensureKeyExists('parent', options);
+  helper.checkFnExists('doctype', options);
+  helper.checkFnExists('instruction', options);
+  helper.checkFnExists('cdata', options);
+  helper.checkFnExists('comment', options);
+  helper.checkFnExists('text', options);
+  helper.checkFnExists('instructionName', options);
+  helper.checkFnExists('elementName', options);
+  helper.checkFnExists('attributeName', options);
+  helper.checkFnExists('attributeValue', options);
+  helper.checkFnExists('attributes', options);
   return options;
 }
 
@@ -52,7 +62,8 @@ function nativeType(value) {
   return value;
 }
 
-function addField(type, value, options) {
+function addField(type, value) {
+  var key;
   if (options.compact) {
     if (!currentElement[options[type + 'Key']] && options.alwaysArray) {
       currentElement[options[type + 'Key']] = [];
@@ -60,6 +71,22 @@ function addField(type, value, options) {
     if (currentElement[options[type + 'Key']] && !(currentElement[options[type + 'Key']] instanceof Array)) {
       currentElement[options[type + 'Key']] = [currentElement[options[type + 'Key']]];
     }
+    if (type + 'Fn' in options && typeof value === 'string') {
+      value = options[type + 'Fn'](value);
+    }
+    if (type === 'instruction' && ('instructionFn' in options || 'instructionNameFn' in options)) {
+      for (key in value) {
+        if (value.hasOwnProperty(key)) {
+          if ('instructionFn' in options) {
+            value[key] = options.instructionFn(value[key], key, currentElement);
+          } else {
+            var temp = value[key];
+            delete value[key];
+            value[options.instructionNameFn(key, currentElement)] = temp;
+          }
+        }
+      }
+    }
     if (currentElement[options[type + 'Key']] instanceof Array) {
       currentElement[options[type + 'Key']].push(value);
     } else {
@@ -69,21 +96,30 @@ function addField(type, value, options) {
     if (!currentElement[options.elementsKey]) {
       currentElement[options.elementsKey] = [];
     }
-    var key, element = {};
+    var element = {};
     element[options.typeKey] = type;
-    if (type === 'instruction' && typeof value === 'object') {
+    if (type === 'instruction') {
       for (key in value) {
         if (value.hasOwnProperty(key)) {
           break;
         }
       }
-      element[options.nameKey] = key;
+      element[options.nameKey] = 'instructionNameFn' in options ? options.instructionNameFn(key, currentElement) : key;
       if (options.instructionHasAttributes) {
         element[options.attributesKey] = value[key][options.attributesKey];
+        if ('attributeNameFn' in options) {
+          element[options.attributesKey] = options[type + 'Fn'](element[options.attributesKey]);
+        }
       } else {
+        if (type + 'Fn' in options) {
+          value[key] = options[type + 'Fn'](value[key]);
+        }
         element[options[type + 'Key']] = value[key];
       }
     } else {
+      if (type + 'Fn' in options) {
+        value = options[type + 'Fn'](value);
+      }
       element[options[type + 'Key']] = value;
     }
     if (options.addParent) {
@@ -93,6 +129,27 @@ function addField(type, value, options) {
   }
 }
 
+function manipulateAttributes(attributes) {
+  if ('attributesFn' in options && attributes) {
+    attributes = options.attributesFn(attributes, currentElement);
+  }
+  if ((options.trim || 'attributeValueFn' in options || 'attributeNameFn' in options) && attributes) {
+    var key;
+    for (key in attributes) {
+      if (attributes.hasOwnProperty(key)) {
+        if (options.trim) attributes[key] = attributes[key].trim();
+        if ('attributeValueFn' in options) attributes[key] = options.attributeValueFn(attributes[key], key, currentElement);
+        if ('attributeNameFn' in options) {
+          var temp = attributes[key];
+          delete attributes[key];
+          attributes[options.attributeNameFn(key, attributes[key], currentElement)] = temp;
+        }
+      }
+    }
+  }
+  return attributes;
+}
+
 function onInstruction(instruction) {
   var attributes = {};
   if (instruction.body && (instruction.name.toLowerCase() === 'xml' || options.instructionHasAttributes)) {
@@ -101,6 +158,7 @@ function onInstruction(instruction) {
     while ((match = attrsRegExp.exec(instruction.body)) !== null) {
       attributes[match[1]] = match[2] || match[3] || match[4];
     }
+    attributes = manipulateAttributes(attributes);
   }
   if (instruction.name.toLowerCase() === 'xml') {
     if (options.ignoreDeclaration) {
@@ -127,27 +185,25 @@ function onInstruction(instruction) {
     } else {
       value[instruction.name] = instruction.body;
     }
-    addField('instruction', value, options);
+    addField('instruction', value);
   }
 }
 
 function onStartElement(name, attributes) {
-  var key, element;
+  var element;
   if (typeof name === 'object') {
     attributes = name.attributes;
     name = name.name;
   }
-  if (options.trim && attributes) {
-    for (key in attributes) {
-      if (attributes.hasOwnProperty(key)) {
-        attributes[key] = attributes[key].trim();
-      }
-    }
+  attributes = manipulateAttributes(attributes);
+  if ('elementNameFn' in options) {
+    name = options.elementNameFn(name, currentElement);
   }
   if (options.compact) {
     element = {};
     if (!options.ignoreAttributes && attributes && Object.keys(attributes).length) {
       element[options.attributesKey] = {};
+      var key;
       for (key in attributes) {
         if (attributes.hasOwnProperty(key)) {
           element[options.attributesKey][key] = attributes[key];
@@ -202,7 +258,7 @@ function onText(text) {
   if (options.sanitize) {
     text = text.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
   }
-  addField('text', text, options);
+  addField('text', text);
 }
 
 function onComment(comment) {
@@ -212,7 +268,7 @@ function onComment(comment) {
   if (options.trim) {
     comment = comment.trim();
   }
-  addField('comment', comment, options);
+  addField('comment', comment);
 }
 
 function onEndElement(name) {
@@ -230,7 +286,7 @@ function onCdata(cdata) {
   if (options.trim) {
     cdata = cdata.trim();
   }
-  addField('cdata', cdata, options);
+  addField('cdata', cdata);
 }
 
 function onDoctype(doctype) {
@@ -241,7 +297,7 @@ function onDoctype(doctype) {
   if (options.trim) {
     doctype = doctype.trim();
   }
-  addField('doctype', doctype, options);
+  addField('doctype', doctype);
 }
 
 function onError(error) {
diff --git a/test/test-items.js b/test/test-items.js
index 30d2f3c..5335d92 100644
--- a/test/test-items.js
+++ b/test/test-items.js
@@ -20,10 +20,15 @@ var cases = [
     js1: {"_declaration":{},"a":{"b":{}}},
     js2: {"declaration":{},"elements":[{"type":"element","name":"a","elements":[{"type":"element","name":"b"}]}]}
   }, {
-    desc: 'processing instruction <?go there>',
+    desc: 'processing instruction <?go there?>',
     xml: '<?go there?>',
     js1: {"_instruction":{"go": "there"}},
     js2: {"elements":[{"type":"instruction","name":"go","instruction":"there"}]}
+  }, {
+    desc: '2 processing instructions <?go there?><?come here?>',
+    xml: '<?go there?><?come here?>',
+    js1: {"_instruction":[{"go": "there"},{"come": "here"}]},
+    js2: {"elements":[{"type":"instruction","name":"go","instruction":"there"},{"type":"instruction","name":"come","instruction":"here"}]}
   }, {
     desc: 'should convert comment',
     xml: '<!-- \t Hello, World! \t -->',
@@ -100,21 +105,24 @@ var cases = [
 module.exports = function (direction, options) {
   var i, tests = [];
   options = options || {};
-  function applyOptions (obj, fullKey) {
-    var key, fn;
+  function applyOptions (obj, pathKey) {
+    var key, fullKey;
+    pathKey = pathKey || '';
     if (obj instanceof Array) {
       obj = obj.filter(function (el) {
         return !(options.ignoreText && el.type === 'text' || options.ignoreComment && el.type === 'comment' || options.ignoreCdata && el.type === 'cdata'
         || options.ignoreDoctype && el.type === 'doctype' || options.ignoreDeclaration && el.type === 'declaration' || options.ignoreInstruction && el.type === 'instruction');
       }).map(function (el) {
-        return manipulate(el, fullKey);
+        return manipulate(el, pathKey);
       });
     } else if (typeof obj === 'object') {
       for (key in obj) {
-        fullKey = (fullKey? fullKey + '.' : '') + key;
+        fullKey = (pathKey ? pathKey + '.' : '') + key;
         if (options.compact && options.alwaysArray && !(obj[key] instanceof Array) && key !== '_declaration' && (key === '_instruction' || fullKey.indexOf('_instruction') < 0) && fullKey.indexOf('_attributes') < 0) {
           obj[key] = [obj[key]];
         }
+        key = applyNameCallbacks(obj, key, pathKey.split('.').pop());
+        key = applyAttributesCallback(obj, key, pathKey.split('.').pop());
         if (key.indexOf('_') === 0 && obj[key] instanceof Array) {
           obj[key] = obj[key].map(function (el) {
             return manipulate(el, fullKey);
@@ -154,10 +162,13 @@ module.exports = function (direction, options) {
       // }
     }
     return obj;
-    function manipulate(x, key) {
-      if (x instanceof Array || typeof x === 'object') {
-        return applyOptions(x, key);
+    function manipulate(x, fullKey) {
+      if (x instanceof Array) {
+        return applyOptions(x, fullKey);
+      } if (typeof x === 'object') {
+        return applyOptions(x, fullKey);
       } else if (typeof x === 'string') {
+        x = applyValueCallbacks(x, fullKey.split('.').pop(), fullKey.split('.')[fullKey.split('.').length - 2] || '');
         return options.trim? x.trim() : x;
       } else if (typeof x === 'number' || typeof x === 'boolean') {
         return options.nativeType? x.toString() : x;
@@ -176,15 +187,57 @@ module.exports = function (direction, options) {
     }
     return js;
   }
+  function applyNameCallbacks(obj, key, parentKey) {
+    if ('instructionNameFn' in options && (options.compact && parentKey === '_instruction' || !options.compact && obj.type === 'instruction')
+      || 'elementNameFn' in options && (options.compact && key.indexOf('_') < 0 && parentKey !== '_attributes' && parentKey !== '_instruction' || !options.compact && obj.type === 'element')) {
+      if (options.compact) {
+        var temp = obj[key];
+        delete obj[key];
+        key = 'elementNameFn' in options ? options.elementNameFn(key) : options.instructionNameFn(key);
+        obj[key] = temp;
+      } else {
+        obj.name = 'elementNameFn' in options ? options.elementNameFn(obj.name) : options.instructionNameFn(obj.name);
+      }
+    }
+    return key;
+  }
+  function applyAttributesCallback(obj, key, parentKey) {
+    if (('attributeNameFn' in options || 'attributeValueFn' in options) && (parentKey === '_attributes' || parentKey === 'attributes')) {
+      if ('attributeNameFn' in options) {
+        var temp = obj[key];
+        delete obj[key];
+        key = options.attributeNameFn(key);
+        obj[key] = temp;
+      }
+      if ('attributeValueFn' in options) {
+        obj[key] = options.attributeValueFn(obj[key]);
+      }
+    }
+    if ('attributesFn' in options && (key === '_attributes' || key === 'attributes')) {
+      obj[key] = options.attributesFn(obj[key]);
+    }
+    return key;
+  }
+  function applyValueCallbacks(value, key, parentKey) {
+    var fn;
+    for (fn in options) {
+      if (fn.match(/Fn$/) && !fn.match(/NameFn$/)) {
+        var callbackName = (options.compact ? '_' : '') + fn.replace('Fn', '');
+        if (key === callbackName || parentKey === callbackName) {
+          value = options[fn](value);
+        }
+      }
+    }
+    return value;
+  }
   for (i = 0; i < cases.length; ++i) {
     tests.push({desc: cases[i].desc, xml: null, js: null});
     tests[i].js = options.compact ? cases[i].js1 : cases[i].js2;
+    tests[i].xml = cases[i].xml;
     if (direction === 'xml2js') {
       tests[i].js = applyOptions(JSON.parse(JSON.stringify(tests[i].js)));
       tests[i].js = applyKeyNames(tests[i].js);
-    }
-    tests[i].xml = cases[i].xml;
-    if (direction === 'js2xml') {
+    } else if (direction === 'js2xml') {
       if (!('spaces' in options) || options.spaces === 0 || typeof options.spaces === 'boolean') { tests[i].xml = tests[i].xml.replace(/>\n\v*/gm, '>'); }
       if ('spaces' in options && options.spaces !== 0 && typeof options.spaces === 'number') { tests[i].xml = tests[i].xml.replace(/\v/g, Array(options.spaces + 1).join(' ')); }
       if ('spaces' in options && typeof options.spaces === 'string') { tests[i].xml = tests[i].xml.replace(/\v/g, options.spaces); }
diff --git a/test/xml2js-callbacks_test.js b/test/xml2js-callbacks_test.js
new file mode 100644
index 0000000..6127da4
--- /dev/null
+++ b/test/xml2js-callbacks_test.js
@@ -0,0 +1,295 @@
+var convert = require('../lib');
+var testItems = require('./test-items');
+
+/*global describe,it,expect*/
+
+function manipulate(val) {
+  return val.toUpperCase();
+}
+
+function manipulateAttribute(obj) {
+  var key, temp;
+  for (key in obj) {
+    temp = obj[key];
+    delete obj[key];
+    obj[key.toUpperCase()] = temp.toUpperCase();
+  }
+  return obj;
+}
+
+describe('Testing xml2js.js:', function () {
+
+  describe('Adding function callbacks, options = {compact: false}', function () {
+
+    describe('options = {doctypeFn: manipulate}', function () {
+
+      var options = {compact: false, doctypeFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionFn: manipulate}', function () {
+
+      var options = {compact: false, instructionFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+          // console.log(JSON.stringify(convert.xml2js(test.xml, options)));
+        });
+      });
+
+    });
+
+    describe('options = {cdataFn: manipulate}', function () {
+
+      var options = {compact: false, cdataFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {commentFn: manipulate}', function () {
+
+      var options = {compact: false, commentFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {textFn: manipulate}', function () {
+
+      var options = {compact: false, textFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionNameFn: manipulate}', function () {
+
+      var options = {compact: false, instructionNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {elementNameFn: manipulate}', function () {
+
+      var options = {compact: false, elementNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributeNameFn: manipulate}', function () {
+
+      var options = {compact: false, attributeNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributeValueFn: manipulate}', function () {
+
+      var options = {compact: false, attributeValueFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributesFn: manipulateAttribute}', function () {
+
+      var options = {compact: false, attributesFn: manipulateAttribute};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {doctypeFn: manipulate, instructionFn: manipulate, cdataFn: manipulate, commentFn: manipulate, textFn: manipulate}', function () {
+
+      var options = {compact: false, doctypeFn: manipulate, instructionFn: manipulate, cdataFn: manipulate, commentFn: manipulate, textFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionNameFn: manipulate, elementNameFn: manipulate, attributeNameFn: manipulate, attributeValueFn: manipulate}', function () {
+
+      var options = {compact: false, instructionNameFn: manipulate, elementNameFn: manipulate, attributeNameFn: manipulate, attributeValueFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+  });
+
+  describe('Adding function callbacks, options = {compact: true}', function () {
+
+    describe('options = {doctypeFn: manipulate}', function () {
+
+      var options = {compact: true, doctypeFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionFn: manipulate}', function () {
+
+      var options = {compact: true, instructionFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {cdataFn: manipulate}', function () {
+
+      var options = {compact: true, cdataFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {commentFn: manipulate}', function () {
+
+      var options = {compact: true, commentFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {textFn: manipulate}', function () {
+
+      var options = {compact: true, textFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionNameFn: manipulate}', function () {
+
+      var options = {compact: true, instructionNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {elementNameFn: manipulate}', function () {
+
+      var options = {compact: true, elementNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributeNameFn: manipulate}', function () {
+
+      var options = {compact: true, attributeNameFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributeValueFn: manipulate}', function () {
+
+      var options = {compact: true, attributeValueFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {attributesFn: manipulateAttribute}', function () {
+
+      var options = {compact: true, attributesFn: manipulateAttribute};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {doctypeFn: manipulate, instructionFn: manipulate, cdataFn: manipulate, commentFn: manipulate, textFn: manipulate}', function () {
+
+      var options = {compact: true, doctypeFn: manipulate, instructionFn: manipulate, cdataFn: manipulate, commentFn: manipulate, textFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+    describe('options = {instructionNameFn: manipulate, elementNameFn: manipulate, attributeNameFn: manipulate, attributeValueFn: manipulate}', function () {
+
+      var options = {compact: true, instructionNameFn: manipulate, elementNameFn: manipulate, attributeNameFn: manipulate, attributeValueFn: manipulate};
+      testItems('xml2js', options).forEach(function (test) {
+        it(test.desc, function () {
+          expect(convert.xml2js(test.xml, options)).toEqual(test.js);
+        });
+      });
+
+    });
+
+  });
+
+});