diff --git a/readme.md b/readme.md
index acf44a1..73bfa27 100644
--- a/readme.md
+++ b/readme.md
@@ -53,7 +53,7 @@ Usually you can find the user agent in:
 ## Constructor
 When you call `UAParser` with the `new` keyword `UAParser` will return a new instance with an empty result object, you have to call one of the available methods to get the information from the user-agent string.
 Like so:
-* `new UAParser([user-agent:string][,extensions:object])`
+* `new UAParser([user-agent:string][,extensions:object][,headers:object(since@1.1)])`
 ```js
 let parser = new UAParser("user-agent"); // you need to pass the user-agent for nodejs
 console.log(parser); // {}
@@ -70,7 +70,7 @@ console.log(parserResults);
 ```
 
 When you call UAParser without the `new` keyword, it will automatically call `getResult()` function and return the parsed results.
-* `UAParser([user-agent:string][,extensions:object])`
+* `UAParser([user-agent:string][,extensions:object][,headers:object(since@1.1)])`
     * returns result object `{ ua: '', browser: {}, cpu: {}, device: {}, engine: {}, os: {} }`
 
 ## Methods
@@ -293,16 +293,17 @@ engine.toString();                  // "Blink 28.0.1500.95"
 
 If you want to detect something that's not currently provided by UAParser.js (eg: bots, specific apps, etc), you can pass a list of regexes to extend internal UAParser.js regexes with your own.
 
-* `UAParser([uastring,] extensions)`
+* `UAParser([uastring,] extensions [,headers:object(since@1.1)])`
 
 ```js
 // Example:
 let myOwnListOfBrowsers = [
-    [/(mybrowser)\/([\w\.]+)/i], [UAParser.BROWSER.NAME, UAParser.BROWSER.VERSION]
+    [/(mybrowser)\/([\w\.]+)/i], [UAParser.BROWSER.NAME, UAParser.BROWSER.VERSION, ['type', 'bot']]
 ];
 let myParser = new UAParser({ browser: myOwnListOfBrowsers });
 let myUA = 'Mozilla/5.0 MyBrowser/1.3';
-console.log(myParser.setUA(myUA).getBrowser());  // {name: "MyBrowser", version: "1.3"}
+console.log(myParser.setUA(myUA).getBrowser());  // {name: "MyBrowser", version: "1.3", major: "1", type : "bot"}
+console.log(myParser.getBrowser().is('bot'));    // true
 
 // Another example:
 let myOwnListOfDevices = [
diff --git a/src/ua-parser.js b/src/ua-parser.js
index a219a38..7a3dc7a 100755
--- a/src/ua-parser.js
+++ b/src/ua-parser.js
@@ -37,6 +37,7 @@
         SMARTTV     = 'smarttv',
         WEARABLE    = 'wearable',
         EMBEDDED    = 'embedded',
+        USER_AGENT  = 'user-agent',
         UA_MAX_LENGTH = 350;
 
     var AMAZON  = 'Amazon',
@@ -71,11 +72,7 @@
     var extend = function (regexes, extensions) {
             var mergedRegexes = {};
             for (var i in regexes) {
-                if (extensions[i] && extensions[i].length % 2 === 0) {
-                    mergedRegexes[i] = extensions[i].concat(regexes[i]);
-                } else {
-                    mergedRegexes[i] = regexes[i];
-                }
+                mergedRegexes[i] = extensions[i] && extensions[i].length % 2 === 0 ? extensions[i].concat(regexes[i]) : regexes[i];
             }
             return mergedRegexes;
         },
@@ -89,6 +86,11 @@
         has = function (str1, str2) {
             return typeof str1 === STR_TYPE ? lowerize(str2).indexOf(lowerize(str1)) !== -1 : false;
         },
+        isExtensions = function (obj) {
+            for (var prop in obj) {
+                return /^(browser|cpu|device|engine|os)$/.test(prop);
+            }
+        },
         lowerize = function (str, rgx) {
             return typeof(str) === STR_TYPE ? str.toLowerCase().replace((rgx ? new RegExp(rgx, 'i') : EMPTY), EMPTY) : str;
         },
@@ -803,84 +805,83 @@
         return callback(this.data);
     };
     UAItem.createUAData = function (data) {
-        return (function () {
-            var propIs = data.propIs;
-            var ignoreIs = data.ignoreIs;
-            var propToStr = data.propToStr;
-            var UAData = function () {
-                for (var i in data.props) {
-                    this[data.props[i]] = undefined;
+        var is_ignoreProps = data.is_ignoreProps,
+            is_ignoreRgx = data.is_ignoreRgx,
+            toString_props = data.toString_props;
+
+        var UAData = function () {
+            for (var i in data.init_props) {
+                this[data.init_props[i]] = undefined;
+            }
+        };
+        UAData.prototype.is = function (strToCheck) {
+            var is = false;
+            for (var i in this) {
+                if (this.hasOwnProperty(i) && !is_ignoreProps[i] && lowerize(this[i], is_ignoreRgx) === lowerize(strToCheck, is_ignoreRgx)) {
+                    is = true;
+                    if (strToCheck != UNDEF_TYPE) break;
+                } else if (strToCheck == UNDEF_TYPE && is) {
+                    is = !is;
+                    break;
                 }
-            };
-            UAData.prototype.is = function (strToCheck) {
-                var is = false;
-                for (var i in propIs) {
-                    if (lowerize(this[propIs[i]], ignoreIs) === lowerize(strToCheck, ignoreIs)) {
-                        is = true;
-                        if (strToCheck != UNDEF_TYPE) break;
-                    } else if (strToCheck == UNDEF_TYPE && is) {
-                        is = !is;
-                        break;
-                    }
+            }
+            return is;
+        };
+        UAData.prototype.toString = function () {
+            var str = EMPTY;
+            for (var i in toString_props) {
+                if (typeof(this[toString_props[i]]) !== UNDEF_TYPE) {
+                    str += (str ? ' ' : EMPTY) + this[toString_props[i]];
                 }
-                return is;
-            };
-            UAData.prototype.toString = function () {
-                var str = EMPTY;
-                for (var i in propToStr) {
-                    if (typeof(this[propToStr[i]]) !== UNDEF_TYPE) {
-                        str += (str ? ' ' : EMPTY) + this[propToStr[i]];
-                    }
-                }
-                return str ? str : UNDEF_TYPE;
-            };
-            return new UAData();
-        })(data);
+            }
+            return str ? str : UNDEF_TYPE;
+        };
+        return new UAData();
     };
 
     function UABrowser () {
         this.data = UAItem.createUAData({
-            props : [NAME, VERSION, MAJOR],
-            propIs : [NAME],
-            ignoreIs : ' ?browser$',
-            propToStr : [NAME, VERSION]
+            init_props : [NAME, VERSION, MAJOR],
+            is_ignoreProps : [VERSION, MAJOR],
+            is_ignoreRgx : ' ?browser$',
+            toString_props : [NAME, VERSION]
         });
     }
     UABrowser.prototype = new UAItem();
 
     function UACPU () {
         this.data = UAItem.createUAData({
-            props : [ARCHITECTURE],
-            propIs : [ARCHITECTURE],
-            propToStr : [ARCHITECTURE]
+            init_props : [ARCHITECTURE],
+            is_ignoreProps : [],
+            toString_props : [ARCHITECTURE]
         });
     }
     UACPU.prototype = new UAItem();
 
     function UADevice () {
         this.data = UAItem.createUAData({
-            props : [TYPE, MODEL, VENDOR],
-            propIs : [TYPE, MODEL, VENDOR],
-            propToStr : [VENDOR, MODEL]
+            init_props : [TYPE, MODEL, VENDOR],
+            is_ignoreProps : [],
+            toString_props : [VENDOR, MODEL]
         });
     }
     UADevice.prototype = new UAItem();
 
     function UAEngine () {
         this.data = UAItem.createUAData({
-            props : [NAME, VERSION],
-            propIs : [NAME],
-            propToStr : [NAME, VERSION]
+            init_props : [NAME, VERSION],
+            is_ignoreProps : [VERSION],
+            toString_props : [NAME, VERSION]
         });
     }
     UAEngine.prototype = new UAItem();
 
     function UAOS () {
         this.data = UAItem.createUAData({
-            props : [NAME, VERSION],
-            propIs : [NAME],
-            ignoreIs : ' ?os$',
-            propToStr : [NAME, VERSION]
+            init_props : [NAME, VERSION],
+            is_ignoreProps : [VERSION],
+            is_ignoreRgx : ' ?os$',
+            toString_props : [NAME, VERSION]
         });
     }
     UAOS.prototype = new UAItem();
@@ -897,18 +898,30 @@
     }
     UAResult.prototype = new UAItem();
 
-    function UAParser (ua, extensions) {
+    function UAParser (ua, extensions, headers) {
 
         if (typeof ua === OBJ_TYPE) {
-            extensions = ua;
+            if (isExtensions(ua)) {
+                if (typeof extensions === OBJ_TYPE) {
+                    headers = extensions;               // case UAParser(extensions, headers)           
+                }
+                extensions = ua;                        // case UAParser(extensions)
+            } else {
+                headers = ua;                           // case UAParser(headers)
+            }
             ua = undefined;
+        } else if (typeof ua === STR_TYPE && !isExtensions(extensions)) {
+            headers = extensions;                       // case UAParser(ua, headers)
+            extensions = undefined;
         }
+        
         if (!(this instanceof UAParser)) {
-            return new UAParser(ua, extensions).getResult();
+            return new UAParser(ua, extensions, headers).getResult();
         }
-
         var _navigator = (typeof window !== UNDEF_TYPE && window.navigator) ? window.navigator : undefined;
-        var _ua = ua || ((_navigator && _navigator.userAgent) ? _navigator.userAgent : EMPTY);
+
+        // _ua = user-supplied string || window.navigator.userAgent || user-agent header || empty
+        var _ua = ua || ((_navigator && _navigator.userAgent) ? _navigator.userAgent : (!ua && headers && headers[USER_AGENT] ? headers[USER_AGENT] : EMPTY));
         var _uach = (_navigator && _navigator.userAgentData) ? _navigator.userAgentData : undefined;
         var _rgxmap = extensions ? extend(regexes, extensions) : regexes;
 
diff --git a/test/test.js b/test/test.js
index 7b4e4a4..339f3c3 100644
--- a/test/test.js
+++ b/test/test.js
@@ -106,6 +106,25 @@ describe('Extending Regex', function () {
     parser2.setUA(uaString);
     assert.strictEqual(parser2.getBrowser().name, 'MyOwnBrowser');
     assert.strictEqual(parser1.getBrowser().version, '1.3');
+
+    let myOwnListOfBrowsers = [
+        [/(mybrowser)\/([\w\.]+)/i], [UAParser.BROWSER.NAME, UAParser.BROWSER.VERSION, ['type', 'bot']]
+    ];
+    let myParser = new UAParser({ browser: myOwnListOfBrowsers });
+    let myUA = 'Mozilla/5.0 MyBrowser/1.3';
+    assert.deepEqual(myParser.setUA(myUA).getBrowser(), {name: "MyBrowser", version: "1.3", major: "1", type : "bot"});
+    assert.strictEqual(myParser.getBrowser().is('bot'), true);
+    
+    let myOwnListOfDevices = [
+        [/(mytab) ([\w ]+)/i], [UAParser.DEVICE.VENDOR, UAParser.DEVICE.MODEL, [UAParser.DEVICE.TYPE, UAParser.DEVICE.TABLET]],
+        [/(myphone)/i], [UAParser.DEVICE.VENDOR, [UAParser.DEVICE.TYPE, UAParser.DEVICE.MOBILE]]
+    ];
+    let myParser2 = new UAParser({
+        browser: myOwnListOfBrowsers,
+        device: myOwnListOfDevices
+    });
+    let myUA2 = 'Mozilla/5.0 MyTab 14 Pro Max';
+    assert.deepEqual(myParser2.setUA(myUA2).getDevice(), {vendor: "MyTab", model: "14 Pro Max", type: "tablet"});
 });
 
 describe('User-agent length', function () {
@@ -248,25 +267,72 @@ describe('is() utility method', function () {
 });
 
 describe('toString() utility method', function () {
-    let uap = new UAParser('Mozilla/5.0 (Mobile; Windows Phone 8.1; Android 4.0; ARM; Trident/7.0; Touch; rv:11.0; IEMobile/11.0; NOKIA; Lumia 635) like iPhone OS 7_0_3 Mac OS X AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537');
-    assert.strictEqual(uap.getBrowser().name, "IEMobile");
-    assert.strictEqual(uap.getBrowser().version, "11.0");
-    assert.strictEqual(uap.getBrowser().major, "11");
-    assert.strictEqual(uap.getBrowser().toString(), "IEMobile 11.0");
+    it('Should return full name', function () {
+        let uap = new UAParser('Mozilla/5.0 (Mobile; Windows Phone 8.1; Android 4.0; ARM; Trident/7.0; Touch; rv:11.0; IEMobile/11.0; NOKIA; Lumia 635) like iPhone OS 7_0_3 Mac OS X AppleWebKit/537 (KHTML, like Gecko) Mobile Safari/537');
+        assert.strictEqual(uap.getBrowser().name, "IEMobile");
+        assert.strictEqual(uap.getBrowser().version, "11.0");
+        assert.strictEqual(uap.getBrowser().major, "11");
+        assert.strictEqual(uap.getBrowser().toString(), "IEMobile 11.0");
 
-    assert.strictEqual(uap.getCPU().architecture, "arm");
-    assert.strictEqual(uap.getCPU().toString(), "arm");
+        assert.strictEqual(uap.getCPU().architecture, "arm");
+        assert.strictEqual(uap.getCPU().toString(), "arm");
 
-    assert.strictEqual(uap.getDevice().vendor, "Nokia");
-    assert.strictEqual(uap.getDevice().model, "Lumia 635");
-    assert.strictEqual(uap.getDevice().type, "mobile");
-    assert.strictEqual(uap.getDevice().toString(), "Nokia Lumia 635");
+        assert.strictEqual(uap.getDevice().vendor, "Nokia");
+        assert.strictEqual(uap.getDevice().model, "Lumia 635");
+        assert.strictEqual(uap.getDevice().type, "mobile");
+        assert.strictEqual(uap.getDevice().toString(), "Nokia Lumia 635");
 
-    assert.strictEqual(uap.getEngine().name, "Trident");
-    assert.strictEqual(uap.getEngine().version, "7.0");
-    assert.strictEqual(uap.getEngine().toString(), "Trident 7.0");
+        assert.strictEqual(uap.getEngine().name, "Trident");
+        assert.strictEqual(uap.getEngine().version, "7.0");
+        assert.strictEqual(uap.getEngine().toString(), "Trident 7.0");
 
-    assert.strictEqual(uap.getOS().name, "Windows Phone");
-    assert.strictEqual(uap.getOS().version, "8.1");
-    assert.strictEqual(uap.getOS().toString(), "Windows Phone 8.1");
+        assert.strictEqual(uap.getOS().name, "Windows Phone");
+        assert.strictEqual(uap.getOS().version, "8.1");
+        assert.strictEqual(uap.getOS().toString(), "Windows Phone 8.1");
+    });
+});
+
+describe('Read user-agent data from req.headers', function () {
+    const ua = 'Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Win64; x64; Trident/6.0)';
+    const ext = {
+        engine : [
+            [/(msie)/i], [[UAParser.ENGINE.NAME, 'Custom Browser 1']],
+            [/(edge)/i], [[UAParser.ENGINE.NAME, 'Custom Browser 2']]
+        ]
+    };
+    const req = { 
+        headers : {
+            'user-agent' : 'Mozilla/5.0 (Windows NT 6.4; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.143 Safari/537.36 Edge/12.0'
+        }
+    };
+
+    it('Can be called with UAParser(ua)', function () {    
+        let engine = UAParser(ua).engine;
+        assert.strictEqual(engine.name, "Trident");
+    });
+
+    it('Can be called with UAParser(ua, extensions)', function () {    
+        let engine = UAParser(ua, ext).engine;
+        assert.strictEqual(engine.name, "Custom Browser 1");
+    });
+
+    it('Can be called with UAParser(ua, extensions, headers)', function () {    
+        let engine = UAParser(ua, ext, req.headers).engine;
+        assert.strictEqual(engine.name, "Custom Browser 1");
+    });
+
+    it('Can be called with UAParser(ua, headers)', function () {    
+        let engine = UAParser(ua, req.headers).engine;
+        assert.strictEqual(engine.name, "Trident");
+    });
+
+    it('Can be called with UAParser(extensions, headers)', function () {    
+        let engine = UAParser(ext, req.headers).engine;
+        assert.strictEqual(engine.name, "Custom Browser 2");
+    });
+
+    it('Can be called with UAParser(headers)', function () {    
+        let engine = UAParser(req.headers).engine;
+        assert.strictEqual(engine.name, "EdgeHTML");
+    });
 });
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