diff --git a/.travis.yml b/.travis.yml
index 4e34a7b1..d5a11531 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,4 @@
 language: node_js
-dist: trusty
-before_script:
-  - npm install
-node_js: 6
+node_js: 8
 script:
-  - npm test
-  - npm run bench
+  - npm test && npm run bench
diff --git a/dist/fast-json-patch.js b/dist/fast-json-patch.js
index 828e3d1b..945d3f53 100644
--- a/dist/fast-json-patch.js
+++ b/dist/fast-json-patch.js
@@ -1,4 +1,4 @@
-/*! fast-json-patch, version: 2.0.6 */
+/*! fast-json-patch, version: 2.0.7 */
 var jsonpatch =
 /******/ (function(modules) { // webpackBootstrap
 /******/ 	// The module cache
@@ -741,10 +741,10 @@ exports.JsonPatchError = helpers_2.PatchError;
 exports.deepClone = helpers_2._deepClone;
 exports.escapePathComponent = helpers_2.escapePathComponent;
 exports.unescapePathComponent = helpers_2.unescapePathComponent;
-var beforeDict = [];
+var beforeDict = new WeakMap();
 var Mirror = (function () {
     function Mirror(obj) {
-        this.observers = [];
+        this.observers = new Map();
         this.obj = obj;
     }
     return Mirror;
@@ -757,26 +757,13 @@ var ObserverInfo = (function () {
     return ObserverInfo;
 }());
 function getMirror(obj) {
-    for (var i = 0, length = beforeDict.length; i < length; i++) {
-        if (beforeDict[i].obj === obj) {
-            return beforeDict[i];
-        }
-    }
+    return beforeDict.get(obj);
 }
 function getObserverFromMirror(mirror, callback) {
-    for (var j = 0, length = mirror.observers.length; j < length; j++) {
-        if (mirror.observers[j].callback === callback) {
-            return mirror.observers[j].observer;
-        }
-    }
+    return mirror.observers.get(callback);
 }
 function removeObserverFromMirror(mirror, observer) {
-    for (var j = 0, length = mirror.observers.length; j < length; j++) {
-        if (mirror.observers[j].observer === observer) {
-            mirror.observers.splice(j, 1);
-            return;
-        }
-    }
+    mirror.observers.delete(observer.callback);
 }
 /**
  * Detach an observer from an object
@@ -790,15 +777,15 @@ exports.unobserve = unobserve;
  */
 function observe(obj, callback) {
     var patches = [];
-    var root = obj;
     var observer;
     var mirror = getMirror(obj);
     if (!mirror) {
         mirror = new Mirror(obj);
-        beforeDict.push(mirror);
+        beforeDict.set(obj, mirror);
     }
     else {
-        observer = getObserverFromMirror(mirror, callback);
+        var observerInfo = getObserverFromMirror(mirror, callback);
+        observer = observerInfo && observerInfo.observer;
     }
     if (observer) {
         return observer;
@@ -853,7 +840,7 @@ function observe(obj, callback) {
             }
         }
     };
-    mirror.observers.push(new ObserverInfo(callback, observer));
+    mirror.observers.set(callback, new ObserverInfo(callback, observer));
     return observer;
 }
 exports.observe = observe;
@@ -861,13 +848,7 @@ exports.observe = observe;
  * Generate an array of patches from an observer
  */
 function generate(observer) {
-    var mirror;
-    for (var i = 0, length = beforeDict.length; i < length; i++) {
-        if (beforeDict[i].obj === observer.object) {
-            mirror = beforeDict[i];
-            break;
-        }
-    }
+    var mirror = beforeDict.get(observer.object);
     _generate(mirror.value, observer.object, observer.patches, "");
     if (observer.patches.length) {
         core_1.applyPatch(mirror.value, observer.patches);
diff --git a/dist/fast-json-patch.min.js b/dist/fast-json-patch.min.js
index df1eaa9b..ec817fb1 100644
--- a/dist/fast-json-patch.min.js
+++ b/dist/fast-json-patch.min.js
@@ -1,2 +1,2 @@
-/*! fast-json-patch, version: 2.0.6 */
-var jsonpatch=function(a){function b(d){if(c[d])return c[d].exports;var e=c[d]={i:d,l:!1,exports:{}};return a[d].call(e.exports,e,e.exports,b),e.l=!0,e.exports}var c={};return b.m=a,b.c=c,b.i=function(a){return a},b.d=function(a,c,d){b.o(a,c)||Object.defineProperty(a,c,{configurable:!1,enumerable:!0,get:d})},b.n=function(a){var c=a&&a.__esModule?function(){return a['default']}:function(){return a};return b.d(c,'a',c),c},b.o=function(a,b){return Object.prototype.hasOwnProperty.call(a,b)},b.p='',b(b.s=3)}([function(a,b){function c(a,b){return i.call(a,b)}function d(a){if(Array.isArray(a)){for(var b=Array(a.length),d=0;d<b.length;d++)b[d]=''+d;return b}if(Object.keys)return Object.keys(a);var b=[];for(var e in a)c(a,e)&&b.push(e);return b}function e(a){return-1===a.indexOf('/')&&-1===a.indexOf('~')?a:a.replace(/~/g,'~0').replace(/\//g,'~1')}function f(a,b){var d;for(var g in a)if(c(a,g)){if(a[g]===b)return e(g)+'/';if('object'==typeof a[g]&&(d=f(a[g],b),''!=d))return e(g)+'/'+d}return''}function g(a){if(a===void 0)return!0;if(a)if(Array.isArray(a)){for(var b=0,c=a.length;b<c;b++)if(g(a[b]))return!0;}else if('object'==typeof a)for(var e=d(a),f=e.length,b=0;b<f;b++)if(g(a[e[b]]))return!0;return!1}var h=this&&this.__extends||function(a,c){function b(){this.constructor=a}for(var d in c)c.hasOwnProperty(d)&&(a[d]=c[d]);a.prototype=null===c?Object.create(c):(b.prototype=c.prototype,new b)},i=Object.prototype.hasOwnProperty;b.hasOwnProperty=c,b._objectKeys=d;b._deepClone=function(a){switch(typeof a){case'object':return JSON.parse(JSON.stringify(a));case'undefined':return null;default:return a;}},b.isInteger=function(a){for(var b,c=0,d=a.length;c<d;){if(b=a.charCodeAt(c),48<=b&&57>=b){c++;continue}return!1}return!0},b.escapePathComponent=e,b.unescapePathComponent=function(a){return a.replace(/~1/g,'/').replace(/~0/g,'~')},b._getPathRecursive=f,b.getPath=function(a,b){if(a===b)return'/';var c=f(a,b);if(''===c)throw new Error('Object not found in root');return'/'+c},b.hasUndefined=g;var j=function(a){function b(b,c,d,e,f){a.call(this,b),this.message=b,this.name=c,this.index=d,this.operation=e,this.tree=f}return h(b,a),b}(Error);b.PatchError=j},function(a,b,c){function d(a,b){if(''==b)return a;var c={op:'_get',path:b};return e(a,c),c.value}function e(a,c,e,f){if(void 0===e&&(e=!1),void 0===f&&(f=!0),e&&('function'==typeof e?e(c,0,a,c.path):g(c,0)),''===c.path){var h={newDocument:a};if('add'===c.op)return h.newDocument=c.value,h;if('replace'===c.op)return h.newDocument=c.value,h.removed=a,h;if('move'===c.op||'copy'===c.op)return h.newDocument=d(a,c.from),'move'===c.op&&(h.removed=a),h;if('test'===c.op){if(h.test=k(a,c.value),!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h.newDocument=a,h}if('remove'===c.op)return h.removed=a,h.newDocument=null,h;if('_get'===c.op)return c.value=a,h;if(e)throw new b.JsonPatchError('Operation `op` property is not one of operations defined in RFC-6902','OPERATION_OP_INVALID',0,c,a);else return h}else{f||(a=l._deepClone(a));var i,j,o,p=c.path||'',q=p.split('/'),r=a,s=1,t=q.length;for(o='function'==typeof e?e:g;;){if(j=q[s],e&&void 0==i&&(void 0===r[j]?i=q.slice(0,s).join('/'):s==t-1&&(i=c.path),void 0!==i&&o(c,0,a,i)),s++,Array.isArray(r)){if('-'===j)j=r.length;else if(e&&!l.isInteger(j))throw new b.JsonPatchError('Expected an unsigned base-10 integer value, making the new referenced value the array element with the zero-based index','OPERATION_PATH_ILLEGAL_ARRAY_INDEX',0,c.path,c);else l.isInteger(j)&&(j=~~j);if(s>=t){if(e&&'add'===c.op&&j>r.length)throw new b.JsonPatchError('The specified index MUST NOT be greater than the number of elements in the array','OPERATION_VALUE_OUT_OF_BOUNDS',0,c.path,c);var h=n[c.op].call(c,r,j,a);if(!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h}}else if(j&&-1!=j.indexOf('~')&&(j=l.unescapePathComponent(j)),s>=t){var h=m[c.op].call(c,r,j,a);if(!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h}r=r[j]}}}function f(a,c,d,f){if(void 0===f&&(f=!0),d&&!Array.isArray(c))throw new b.JsonPatchError('Patch sequence must be an array','SEQUENCE_NOT_AN_ARRAY');f||(a=l._deepClone(a));for(var g=Array(c.length),h=0,i=c.length;h<i;h++)g[h]=e(a,c[h],d),a=g[h].newDocument;return g.newDocument=a,g}function g(a,c,d,e){if('object'!=typeof a||null===a||Array.isArray(a))throw new b.JsonPatchError('Operation is not an object','OPERATION_NOT_AN_OBJECT',c,a,d);else if(!m[a.op])throw new b.JsonPatchError('Operation `op` property is not one of operations defined in RFC-6902','OPERATION_OP_INVALID',c,a,d);else if('string'!=typeof a.path)throw new b.JsonPatchError('Operation `path` property is not a string','OPERATION_PATH_INVALID',c,a,d);else if(0!==a.path.indexOf('/')&&0<a.path.length)throw new b.JsonPatchError('Operation `path` property must start with "/"','OPERATION_PATH_INVALID',c,a,d);else if(('move'===a.op||'copy'===a.op)&&'string'!=typeof a.from)throw new b.JsonPatchError('Operation `from` property is not present (applicable in `move` and `copy` operations)','OPERATION_FROM_REQUIRED',c,a,d);else if(('add'===a.op||'replace'===a.op||'test'===a.op)&&a.value===void 0)throw new b.JsonPatchError('Operation `value` property is not present (applicable in `add`, `replace` and `test` operations)','OPERATION_VALUE_REQUIRED',c,a,d);else if(('add'===a.op||'replace'===a.op||'test'===a.op)&&l.hasUndefined(a.value))throw new b.JsonPatchError('Operation `value` property is not present (applicable in `add`, `replace` and `test` operations)','OPERATION_VALUE_CANNOT_CONTAIN_UNDEFINED',c,a,d);else if(d)if('add'==a.op){var f=a.path.split('/').length,g=e.split('/').length;if(f!==g+1&&f!==g)throw new b.JsonPatchError('Cannot perform an `add` operation at the desired path','OPERATION_PATH_CANNOT_ADD',c,a,d)}else if('replace'===a.op||'remove'===a.op||'_get'===a.op){if(a.path!==e)throw new b.JsonPatchError('Cannot perform the operation at a path that does not exist','OPERATION_PATH_UNRESOLVABLE',c,a,d);}else if('move'===a.op||'copy'===a.op){var i={op:'_get',path:a.from,value:void 0},j=h([i],d);if(j&&'OPERATION_PATH_UNRESOLVABLE'===j.name)throw new b.JsonPatchError('Cannot perform the operation from a path that does not exist','OPERATION_FROM_UNRESOLVABLE',c,a,d)}}function h(a,c,d){try{if(!Array.isArray(a))throw new b.JsonPatchError('Patch sequence must be an array','SEQUENCE_NOT_AN_ARRAY');if(c)f(l._deepClone(c),l._deepClone(a),d||!0);else{d=d||g;for(var e=0;e<a.length;e++)d(a[e],e,c,void 0)}}catch(a){if(a instanceof b.JsonPatchError)return a;throw a}}var i={strict:!0},j=c(2),k=function(c,a){return j(c,a,i)},l=c(0);b.JsonPatchError=l.PatchError,b.deepClone=l._deepClone;var m={add:function(a,b,c){return a[b]=this.value,{newDocument:c}},remove:function(a,b,c){var d=a[b];return delete a[b],{newDocument:c,removed:d}},replace:function(a,b,c){var d=a[b];return a[b]=this.value,{newDocument:c,removed:d}},move:function(a,b,c){var f=d(c,this.path);f&&(f=l._deepClone(f));var g=e(c,{op:'remove',path:this.from}).removed;return e(c,{op:'add',path:this.path,value:g}),{newDocument:c,removed:f}},copy:function(a,b,c){var f=d(c,this.from);return e(c,{op:'add',path:this.path,value:l._deepClone(f)}),{newDocument:c}},test:function(a,b,c){return{newDocument:c,test:k(a[b],this.value)}},_get:function(a,b,c){return this.value=a[b],{newDocument:c}}},n={add:function(a,b,c){return l.isInteger(b)?a.splice(b,0,this.value):a[b]=this.value,{newDocument:c,index:b}},remove:function(a,b,c){var d=a.splice(b,1);return{newDocument:c,removed:d[0]}},replace:function(a,b,c){var d=a[b];return a[b]=this.value,{newDocument:c,removed:d}},move:m.move,copy:m.copy,test:m.test,_get:m._get};b.getValueByPointer=d,b.applyOperation=e,b.applyPatch=f,b.applyReducer=function(a,c){var d=e(a,c);if(!1===d.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return d.newDocument},b.validator=g,b.validate=h},function(a,b,c){function d(a){return null===a||a===void 0}function e(a){return a&&'object'==typeof a&&'number'==typeof a.length&&('function'!=typeof a.copy||'function'!=typeof a.slice?!1:0<a.length&&'number'!=typeof a[0]?!1:!0)}function f(c,f,l){var m,i;if(d(c)||d(f))return!1;if(c.prototype!==f.prototype)return!1;if(j(c))return!!j(f)&&(c=g.call(c),f=g.call(f),k(c,f,l));if(e(c)){if(!e(f))return!1;if(c.length!==f.length)return!1;for(m=0;m<c.length;m++)if(c[m]!==f[m])return!1;return!0}try{var n=h(c),o=h(f)}catch(a){return!1}if(n.length!=o.length)return!1;for(n.sort(),o.sort(),m=n.length-1;0<=m;m--)if(n[m]!=o[m])return!1;for(m=n.length-1;0<=m;m--)if(i=n[m],!k(c[i],f[i],l))return!1;return typeof c==typeof f}var g=Array.prototype.slice,h=c(5),j=c(4),k=a.exports=function(a,b,c){return c||(c={}),a===b||(a instanceof Date&&b instanceof Date?a.getTime()===b.getTime():a&&b&&('object'==typeof a||'object'==typeof b)?f(a,b,c):c.strict?a===b:a==b)}},function(a,b,c){function d(a){for(var b=0,c=o.length;b<c;b++)if(o[b].obj===a)return o[b]}function e(a,b){for(var c=0,d=a.observers.length;c<d;c++)if(a.observers[c].callback===b)return a.observers[c].observer}function f(a,b){for(var c=0,d=a.observers.length;c<d;c++)if(a.observers[c].observer===b)return void a.observers.splice(c,1)}function g(a){for(var b,c=0,d=o.length;c<d;c++)if(o[c].obj===a.object){b=o[c];break}h(b.value,a.object,a.patches,''),a.patches.length&&l.applyPatch(b.value,a.patches);var e=a.patches;return 0<e.length&&(a.patches=[],a.callback&&a.callback(e)),e}function h(a,b,c,d){if(b!==a){'function'==typeof b.toJSON&&(b=b.toJSON());for(var e=k._objectKeys(b),f=k._objectKeys(a),g=!1,i=!1,j=f.length-1;0<=j;j--){var l=f[j],m=a[l];if(k.hasOwnProperty(b,l)&&(void 0!==b[l]||void 0===m||!1!==Array.isArray(b))){var n=b[l];'object'==typeof m&&null!=m&&'object'==typeof 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c,h=d(a);if(h?c=e(h,b):(h=new p(a),o.push(h)),c)return c;if(c={},h.value=k._deepClone(a),b){c.callback=b,c.next=null;var i=function(){g(c)},j=function(){clearTimeout(c.next),c.next=setTimeout(i)};'undefined'!=typeof window&&(window.addEventListener?(window.addEventListener('mouseup',j),window.addEventListener('keyup',j),window.addEventListener('mousedown',j),window.addEventListener('keydown',j),window.addEventListener('change',j)):(document.documentElement.attachEvent('onmouseup',j),document.documentElement.attachEvent('onkeyup',j),document.documentElement.attachEvent('onmousedown',j),document.documentElement.attachEvent('onkeydown',j),document.documentElement.attachEvent('onchange',j)))}return c.patches=[],c.object=a,c.unobserve=function(){g(c),clearTimeout(c.next),f(h,c),'undefined'!=typeof window&&(window.removeEventListener?(window.removeEventListener('mouseup',j),window.removeEventListener('keyup',j),window.removeEventListener('mousedown',j),window.removeEventListener('keydown',j)):(document.documentElement.detachEvent('onmouseup',j),document.documentElement.detachEvent('onkeyup',j),document.documentElement.detachEvent('onmousedown',j),document.documentElement.detachEvent('onkeydown',j)))},h.observers.push(new q(b,c)),c},b.generate=g,b.compare=function(a,b){var c=[];return h(a,b,c,''),c}},function(a,b){function c(a){return'[object Arguments]'==Object.prototype.toString.call(a)}function d(a){return a&&'object'==typeof a&&'number'==typeof a.length&&Object.prototype.hasOwnProperty.call(a,'callee')&&!Object.prototype.propertyIsEnumerable.call(a,'callee')||!1}var e='[object Arguments]'==function(){return Object.prototype.toString.call(arguments)}();b=a.exports=e?c:d,b.supported=c;b.unsupported=d},function(a,b){function c(a){var b=[];for(var c in a)b.push(c);return b}b=a.exports='function'==typeof Object.keys?Object.keys:c,b.shim=c}]);
\ No newline at end of file
+/*! fast-json-patch, version: 2.0.7 */
+var jsonpatch=function(a){function b(d){if(c[d])return c[d].exports;var e=c[d]={i:d,l:!1,exports:{}};return a[d].call(e.exports,e,e.exports,b),e.l=!0,e.exports}var c={};return b.m=a,b.c=c,b.i=function(a){return a},b.d=function(a,c,d){b.o(a,c)||Object.defineProperty(a,c,{configurable:!1,enumerable:!0,get:d})},b.n=function(a){var c=a&&a.__esModule?function(){return a['default']}:function(){return a};return b.d(c,'a',c),c},b.o=function(a,b){return Object.prototype.hasOwnProperty.call(a,b)},b.p='',b(b.s=3)}([function(a,b){function c(a,b){return i.call(a,b)}function d(a){if(Array.isArray(a)){for(var b=Array(a.length),d=0;d<b.length;d++)b[d]=''+d;return b}if(Object.keys)return Object.keys(a);var b=[];for(var e in a)c(a,e)&&b.push(e);return b}function e(a){return-1===a.indexOf('/')&&-1===a.indexOf('~')?a:a.replace(/~/g,'~0').replace(/\//g,'~1')}function f(a,b){var d;for(var g in a)if(c(a,g)){if(a[g]===b)return e(g)+'/';if('object'==typeof a[g]&&(d=f(a[g],b),''!=d))return e(g)+'/'+d}return''}function g(a){if(a===void 0)return!0;if(a)if(Array.isArray(a)){for(var b=0,c=a.length;b<c;b++)if(g(a[b]))return!0;}else if('object'==typeof a)for(var e=d(a),f=e.length,b=0;b<f;b++)if(g(a[e[b]]))return!0;return!1}var h=this&&this.__extends||function(a,c){function b(){this.constructor=a}for(var d in c)c.hasOwnProperty(d)&&(a[d]=c[d]);a.prototype=null===c?Object.create(c):(b.prototype=c.prototype,new b)},i=Object.prototype.hasOwnProperty;b.hasOwnProperty=c,b._objectKeys=d;b._deepClone=function(a){switch(typeof a){case'object':return JSON.parse(JSON.stringify(a));case'undefined':return null;default:return a;}},b.isInteger=function(a){for(var b,c=0,d=a.length;c<d;){if(b=a.charCodeAt(c),48<=b&&57>=b){c++;continue}return!1}return!0},b.escapePathComponent=e,b.unescapePathComponent=function(a){return a.replace(/~1/g,'/').replace(/~0/g,'~')},b._getPathRecursive=f,b.getPath=function(a,b){if(a===b)return'/';var c=f(a,b);if(''===c)throw new Error('Object not found in root');return'/'+c},b.hasUndefined=g;var j=function(a){function b(b,c,d,e,f){a.call(this,b),this.message=b,this.name=c,this.index=d,this.operation=e,this.tree=f}return h(b,a),b}(Error);b.PatchError=j},function(a,b,c){function d(a,b){if(''==b)return a;var c={op:'_get',path:b};return e(a,c),c.value}function e(a,c,e,f){if(void 0===e&&(e=!1),void 0===f&&(f=!0),e&&('function'==typeof e?e(c,0,a,c.path):g(c,0)),''===c.path){var h={newDocument:a};if('add'===c.op)return h.newDocument=c.value,h;if('replace'===c.op)return h.newDocument=c.value,h.removed=a,h;if('move'===c.op||'copy'===c.op)return h.newDocument=d(a,c.from),'move'===c.op&&(h.removed=a),h;if('test'===c.op){if(h.test=k(a,c.value),!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h.newDocument=a,h}if('remove'===c.op)return h.removed=a,h.newDocument=null,h;if('_get'===c.op)return c.value=a,h;if(e)throw new b.JsonPatchError('Operation `op` property is not one of operations defined in RFC-6902','OPERATION_OP_INVALID',0,c,a);else return h}else{f||(a=l._deepClone(a));var i,j,o,p=c.path||'',q=p.split('/'),r=a,s=1,t=q.length;for(o='function'==typeof e?e:g;;){if(j=q[s],e&&void 0==i&&(void 0===r[j]?i=q.slice(0,s).join('/'):s==t-1&&(i=c.path),void 0!==i&&o(c,0,a,i)),s++,Array.isArray(r)){if('-'===j)j=r.length;else if(e&&!l.isInteger(j))throw new b.JsonPatchError('Expected an unsigned base-10 integer value, making the new referenced value the array element with the zero-based index','OPERATION_PATH_ILLEGAL_ARRAY_INDEX',0,c.path,c);else l.isInteger(j)&&(j=~~j);if(s>=t){if(e&&'add'===c.op&&j>r.length)throw new b.JsonPatchError('The specified index MUST NOT be greater than the number of elements in the array','OPERATION_VALUE_OUT_OF_BOUNDS',0,c.path,c);var h=n[c.op].call(c,r,j,a);if(!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h}}else if(j&&-1!=j.indexOf('~')&&(j=l.unescapePathComponent(j)),s>=t){var h=m[c.op].call(c,r,j,a);if(!1===h.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return h}r=r[j]}}}function f(a,c,d,f){if(void 0===f&&(f=!0),d&&!Array.isArray(c))throw new b.JsonPatchError('Patch sequence must be an array','SEQUENCE_NOT_AN_ARRAY');f||(a=l._deepClone(a));for(var g=Array(c.length),h=0,i=c.length;h<i;h++)g[h]=e(a,c[h],d),a=g[h].newDocument;return g.newDocument=a,g}function g(a,c,d,e){if('object'!=typeof a||null===a||Array.isArray(a))throw new b.JsonPatchError('Operation is not an object','OPERATION_NOT_AN_OBJECT',c,a,d);else if(!m[a.op])throw new b.JsonPatchError('Operation `op` property is not one of operations defined in RFC-6902','OPERATION_OP_INVALID',c,a,d);else if('string'!=typeof a.path)throw new b.JsonPatchError('Operation `path` property is not a string','OPERATION_PATH_INVALID',c,a,d);else if(0!==a.path.indexOf('/')&&0<a.path.length)throw new b.JsonPatchError('Operation `path` property must start with "/"','OPERATION_PATH_INVALID',c,a,d);else if(('move'===a.op||'copy'===a.op)&&'string'!=typeof a.from)throw new b.JsonPatchError('Operation `from` property is not present (applicable in `move` and `copy` operations)','OPERATION_FROM_REQUIRED',c,a,d);else if(('add'===a.op||'replace'===a.op||'test'===a.op)&&a.value===void 0)throw new b.JsonPatchError('Operation `value` property is not present (applicable in `add`, `replace` and `test` operations)','OPERATION_VALUE_REQUIRED',c,a,d);else if(('add'===a.op||'replace'===a.op||'test'===a.op)&&l.hasUndefined(a.value))throw new b.JsonPatchError('Operation `value` property is not present (applicable in `add`, `replace` and `test` operations)','OPERATION_VALUE_CANNOT_CONTAIN_UNDEFINED',c,a,d);else if(d)if('add'==a.op){var f=a.path.split('/').length,g=e.split('/').length;if(f!==g+1&&f!==g)throw new b.JsonPatchError('Cannot perform an `add` operation at the desired path','OPERATION_PATH_CANNOT_ADD',c,a,d)}else if('replace'===a.op||'remove'===a.op||'_get'===a.op){if(a.path!==e)throw new b.JsonPatchError('Cannot perform the operation at a path that does not exist','OPERATION_PATH_UNRESOLVABLE',c,a,d);}else if('move'===a.op||'copy'===a.op){var i={op:'_get',path:a.from,value:void 0},j=h([i],d);if(j&&'OPERATION_PATH_UNRESOLVABLE'===j.name)throw new b.JsonPatchError('Cannot perform the operation from a path that does not exist','OPERATION_FROM_UNRESOLVABLE',c,a,d)}}function h(a,c,d){try{if(!Array.isArray(a))throw new b.JsonPatchError('Patch sequence must be an array','SEQUENCE_NOT_AN_ARRAY');if(c)f(l._deepClone(c),l._deepClone(a),d||!0);else{d=d||g;for(var e=0;e<a.length;e++)d(a[e],e,c,void 0)}}catch(a){if(a instanceof b.JsonPatchError)return a;throw a}}var i={strict:!0},j=c(2),k=function(c,a){return j(c,a,i)},l=c(0);b.JsonPatchError=l.PatchError,b.deepClone=l._deepClone;var m={add:function(a,b,c){return a[b]=this.value,{newDocument:c}},remove:function(a,b,c){var d=a[b];return delete a[b],{newDocument:c,removed:d}},replace:function(a,b,c){var d=a[b];return a[b]=this.value,{newDocument:c,removed:d}},move:function(a,b,c){var f=d(c,this.path);f&&(f=l._deepClone(f));var g=e(c,{op:'remove',path:this.from}).removed;return e(c,{op:'add',path:this.path,value:g}),{newDocument:c,removed:f}},copy:function(a,b,c){var f=d(c,this.from);return e(c,{op:'add',path:this.path,value:l._deepClone(f)}),{newDocument:c}},test:function(a,b,c){return{newDocument:c,test:k(a[b],this.value)}},_get:function(a,b,c){return this.value=a[b],{newDocument:c}}},n={add:function(a,b,c){return l.isInteger(b)?a.splice(b,0,this.value):a[b]=this.value,{newDocument:c,index:b}},remove:function(a,b,c){var d=a.splice(b,1);return{newDocument:c,removed:d[0]}},replace:function(a,b,c){var d=a[b];return a[b]=this.value,{newDocument:c,removed:d}},move:m.move,copy:m.copy,test:m.test,_get:m._get};b.getValueByPointer=d,b.applyOperation=e,b.applyPatch=f,b.applyReducer=function(a,c){var d=e(a,c);if(!1===d.test)throw new b.JsonPatchError('Test operation failed','TEST_OPERATION_FAILED',0,c,a);return d.newDocument},b.validator=g,b.validate=h},function(a,b,c){function d(a){return null===a||a===void 0}function e(a){return a&&'object'==typeof a&&'number'==typeof a.length&&('function'!=typeof a.copy||'function'!=typeof a.slice?!1:0<a.length&&'number'!=typeof a[0]?!1:!0)}function f(c,f,l){var m,i;if(d(c)||d(f))return!1;if(c.prototype!==f.prototype)return!1;if(j(c))return!!j(f)&&(c=g.call(c),f=g.call(f),k(c,f,l));if(e(c)){if(!e(f))return!1;if(c.length!==f.length)return!1;for(m=0;m<c.length;m++)if(c[m]!==f[m])return!1;return!0}try{var n=h(c),o=h(f)}catch(a){return!1}if(n.length!=o.length)return!1;for(n.sort(),o.sort(),m=n.length-1;0<=m;m--)if(n[m]!=o[m])return!1;for(m=n.length-1;0<=m;m--)if(i=n[m],!k(c[i],f[i],l))return!1;return typeof c==typeof f}var g=Array.prototype.slice,h=c(5),j=c(4),k=a.exports=function(a,b,c){return c||(c={}),a===b||(a instanceof Date&&b instanceof Date?a.getTime()===b.getTime():a&&b&&('object'==typeof a||'object'==typeof b)?f(a,b,c):c.strict?a===b:a==b)}},function(a,b,c){function d(a){return o.get(a)}function e(a,b){return a.observers.get(b)}function f(a,b){a.observers.delete(b.callback)}function g(a){var b=o.get(a.object);h(b.value,a.object,a.patches,''),a.patches.length&&l.applyPatch(b.value,a.patches);var c=a.patches;return 0<c.length&&(a.patches=[],a.callback&&a.callback(c)),c}function h(a,b,c,d){if(b!==a){'function'==typeof b.toJSON&&(b=b.toJSON());for(var e=k._objectKeys(b),f=k._objectKeys(a),g=!1,i=!1,j=f.length-1;0<=j;j--){var l=f[j],m=a[l];if(k.hasOwnProperty(b,l)&&(void 0!==b[l]||void 0===m||!1!==Array.isArray(b))){var n=b[l];'object'==typeof m&&null!=m&&'object'==typeof n&&null!=n?h(m,n,c,d+'/'+k.escapePathComponent(l)):m!==n&&(g=!0,c.push({op:'replace',path:d+'/'+k.escapePathComponent(l),value:k._deepClone(n)}))}else c.push({op:'remove',path:d+'/'+k.escapePathComponent(l)}),i=!0}if(i||e.length!=f.length)for(var l,j=0;j<e.length;j++)l=e[j],k.hasOwnProperty(a,l)||void 0===b[l]||c.push({op:'add',path:d+'/'+k.escapePathComponent(l),value:k._deepClone(b[l])})}}var i={strict:!0},j=c(2),k=c(0),l=c(1),m=c(1);b.applyOperation=m.applyOperation,b.applyPatch=m.applyPatch,b.applyReducer=m.applyReducer,b.getValueByPointer=m.getValueByPointer,b.validate=m.validate,b.validator=m.validator;var n=c(0);b.JsonPatchError=n.PatchError,b.deepClone=n._deepClone,b.escapePathComponent=n.escapePathComponent,b.unescapePathComponent=n.unescapePathComponent;var o=new WeakMap,p=function(){return function(a){this.observers=new Map,this.obj=a}}(),q=function(){return function(a,b){this.callback=a,this.observer=b}}();b.unobserve=function(a,b){b.unobserve()},b.observe=function(a,b){var c,h=d(a);if(!h)h=new p(a),o.set(a,h);else{var i=e(h,b);c=i&&i.observer}if(c)return c;if(c={},h.value=k._deepClone(a),b){c.callback=b,c.next=null;var j=function(){g(c)},l=function(){clearTimeout(c.next),c.next=setTimeout(j)};'undefined'!=typeof window&&(window.addEventListener?(window.addEventListener('mouseup',l),window.addEventListener('keyup',l),window.addEventListener('mousedown',l),window.addEventListener('keydown',l),window.addEventListener('change',l)):(document.documentElement.attachEvent('onmouseup',l),document.documentElement.attachEvent('onkeyup',l),document.documentElement.attachEvent('onmousedown',l),document.documentElement.attachEvent('onkeydown',l),document.documentElement.attachEvent('onchange',l)))}return c.patches=[],c.object=a,c.unobserve=function(){g(c),clearTimeout(c.next),f(h,c),'undefined'!=typeof window&&(window.removeEventListener?(window.removeEventListener('mouseup',l),window.removeEventListener('keyup',l),window.removeEventListener('mousedown',l),window.removeEventListener('keydown',l)):(document.documentElement.detachEvent('onmouseup',l),document.documentElement.detachEvent('onkeyup',l),document.documentElement.detachEvent('onmousedown',l),document.documentElement.detachEvent('onkeydown',l)))},h.observers.set(b,new q(b,c)),c},b.generate=g,b.compare=function(a,b){var c=[];return h(a,b,c,''),c}},function(a,b){function c(a){return'[object Arguments]'==Object.prototype.toString.call(a)}function d(a){return a&&'object'==typeof a&&'number'==typeof a.length&&Object.prototype.hasOwnProperty.call(a,'callee')&&!Object.prototype.propertyIsEnumerable.call(a,'callee')||!1}var e='[object Arguments]'==function(){return Object.prototype.toString.call(arguments)}();b=a.exports=e?c:d,b.supported=c;b.unsupported=d},function(a,b){function c(a){var b=[];for(var c in a)b.push(c);return b}b=a.exports='function'==typeof Object.keys?Object.keys:c,b.shim=c}]);
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 9c9d0a71..ae609a3d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "fast-json-patch",
-  "version": "2.0.3",
+  "version": "2.0.7",
   "lockfileVersion": 1,
   "dependencies": {
     "abab": {
diff --git a/package.json b/package.json
index f4816449..cd5e5762 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fast-json-patch",
-  "version": "2.0.6",
+  "version": "2.0.7",
   "description": "Fast implementation of JSON-Patch (RFC-6902) with duplex (observe changes) capabilities",
   "homepage": "https://github.com/Starcounter-Jack/JSON-Patch",
   "keywords": [
diff --git a/src/duplex.ts b/src/duplex.ts
index b0a3979d..1f2498a0 100644
--- a/src/duplex.ts
+++ b/src/duplex.ts
@@ -26,50 +26,38 @@ export interface Observer<T> {
   callback: (patches: Operation[]) => void;
 }
 
-var beforeDict = [];
+var beforeDict = new WeakMap();
 
 class Mirror {
   obj: any;
-  observers = [];
+  observers : Map<Function, ObserverInfo> = new Map();
+  value: Object | Array<any>;
 
-  constructor(obj: any) {
+  constructor(obj: Object) {
     this.obj = obj;
   }
 }
 
 class ObserverInfo {
-  callback: any;
-  observer: any;
+  callback: Function;
+  observer: ObserverInfo;
 
-  constructor(callback, observer) {
+  constructor(callback: Function, observer: ObserverInfo) {
     this.callback = callback;
     this.observer = observer;
   }
 }
 
-function getMirror(obj: any): any {
-  for (var i = 0, length = beforeDict.length; i < length; i++) {
-    if (beforeDict[i].obj === obj) {
-      return beforeDict[i];
-    }
-  }
+function getMirror(obj: Object): Mirror {
+  return beforeDict.get(obj);
 }
 
-function getObserverFromMirror(mirror: any, callback): any {
-  for (var j = 0, length = mirror.observers.length; j < length; j++) {
-    if (mirror.observers[j].callback === callback) {
-      return mirror.observers[j].observer;
-    }
-  }
+function getObserverFromMirror(mirror: Mirror, callback): ObserverInfo {
+  return mirror.observers.get(callback)
 }
 
-function removeObserverFromMirror(mirror: any, observer): any {
-  for (var j = 0, length = mirror.observers.length; j < length; j++) {
-    if (mirror.observers[j].observer === observer) {
-      mirror.observers.splice(j, 1);
-      return;
-    }
-  }
+function removeObserverFromMirror(mirror: Mirror, observer): void {
+  mirror.observers.delete(observer.callback);
 }
 
 /**
@@ -82,17 +70,17 @@ export function unobserve<T>(root: T, observer: Observer<T>) {
 /**
  * Observes changes made to an object, which can then be retrieved using generate
  */
-export function observe<T>(obj: any, callback?: (patches: Operation[]) => void): Observer<T> {
+export function observe<T>(obj: Object|Array<T>, callback?: (patches: Operation[]) => void): Observer<T> {
   var patches = [];
-  var root = obj;
   var observer;
   var mirror = getMirror(obj);
 
   if (!mirror) {
     mirror = new Mirror(obj);
-    beforeDict.push(mirror);
+    beforeDict.set(obj, mirror);
   } else {
-    observer = getObserverFromMirror(mirror, callback);
+    const observerInfo = getObserverFromMirror(mirror, callback);
+    observer = observerInfo && observerInfo.observer;
   }
 
   if (observer) {
@@ -155,7 +143,7 @@ export function observe<T>(obj: any, callback?: (patches: Operation[]) => void):
     }
   };
 
-  mirror.observers.push(new ObserverInfo(callback, observer));
+  mirror.observers.set(callback, new ObserverInfo(callback, observer));
 
   return observer;
 }
@@ -163,14 +151,8 @@ export function observe<T>(obj: any, callback?: (patches: Operation[]) => void):
 /**
  * Generate an array of patches from an observer
  */
-export function generate<T>(observer: Observer<T>): Operation[] {
-  var mirror;
-  for (var i = 0, length = beforeDict.length; i < length; i++) {
-    if (beforeDict[i].obj === observer.object) {
-      mirror = beforeDict[i];
-      break;
-    }
-  }
+export function generate<T>(observer: Observer<Object>): Operation[] {
+  var mirror = beforeDict.get(observer.object);
   _generate(mirror.value, observer.object, observer.patches, "");
   if (observer.patches.length) {
     applyPatch(mirror.value, observer.patches);
@@ -237,7 +219,7 @@ function _generate(mirror, obj, patches, path) {
 /**
  * Create an array of patches from the differences in two objects
  */
-export function compare(tree1: any, tree2: any): Operation[] {
+export function compare(tree1: Object | Array<any>, tree2: Object | Array<any>): Operation[] {
   var patches = [];
   _generate(tree1, tree2, patches, '');
   return patches;
diff --git a/tsconfig.json b/tsconfig.json
index 4e0a4307..78450648 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -3,6 +3,9 @@
         "target": "es5",
         "outDir": "lib/",
         "module": "commonjs",
+        "lib": [
+            "es2016", "dom"
+        ],
         "noEmitHelpers": false,
         "declaration": true,
         "removeComments": false,