diff --git a/dist/flexsearch.compact.js b/dist/flexsearch.compact.js
index 2f18d91..311fe85 100644
--- a/dist/flexsearch.compact.js
+++ b/dist/flexsearch.compact.js
@@ -1,24 +1,27 @@
 /**!
- * FlexSearch.js v0.7.0-pre-alpha (Compact)
+ * FlexSearch.js v0.7.0-beta (Compact)
  * Copyright 2019 Nextapps GmbH
  * Author: Thomas Wilkerling
  * Licence: Apache-2.0
  * https://github.com/nextapps-de/flexsearch
  */
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diff --git a/dist/flexsearch.light.js b/dist/flexsearch.light.js
index d44d0a4..dac0346 100644
--- a/dist/flexsearch.light.js
+++ b/dist/flexsearch.light.js
@@ -1,17 +1,17 @@
 /**!
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+ * FlexSearch.js v0.7.0-beta (Light)
  * Copyright 2019 Nextapps GmbH
  * Author: Thomas Wilkerling
  * Licence: Apache-2.0
  * https://github.com/nextapps-de/flexsearch
  */
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diff --git a/dist/flexsearch.min.js b/dist/flexsearch.min.js
index a2a6024..2db82f7 100644
--- a/dist/flexsearch.min.js
+++ b/dist/flexsearch.min.js
@@ -1,35 +1,31 @@
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+ * FlexSearch.js v0.7.0-beta (Bundle)
  * Copyright 2019 Nextapps GmbH
  * Author: Thomas Wilkerling
  * Licence: Apache-2.0
  * https://github.com/nextapps-de/flexsearch
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+function S(a){R.prototype[a]=R.prototype[a+"Async"]=function(){const b=this,d=[].slice.call(arguments);var c=d[d.length-1];let e;H(c)&&(e=c,d.splice(d.length-1,1));c=new I(function(f){b.g.postMessage({H:a,J:d});"search"===a?b.h=f:f()});return e?(c.then(e),this):c}};function T(a){if(!(this instanceof T))return new T(a);var b;a||(a={});this.G=[];this.g=[];this.u=[];this.register=A();this.key=(b=a.key)&&U(b,this.u)||"id";this.i=y(a.fastupdate,!0);this.store=(b=a.store)&&A();this.A=b&&!0!==b&&[];this.C=(b=a.tag)&&U(b,this.u);this.h=b&&A();this.cache=(b=a.cache)&&new N(b);a.cache=!1;this.m=a.worker;this.async=!1;b=a;a=A();let d=b.doc;if(E(d))d=[d];else if(d.constructor!==Array){var c=d;d=Object.keys(d)}for(let e=0,f,g;e<d.length;e++)f=d[e],E(f)?c&&(g=c[f]):(g=f,
+f=f.field),g=G(g)?Object.assign({},b,g):b,a[f]=this.m?new R(g):new O(g,this.register),this.G[e]=U(f,this.u),this.g[e]=f;if(this.A)for(c=b.store,E(c)&&(c=[c]),b=0;b<c.length;b++)this.A[b]=U(c[b],this.u);this.j=a}function U(a,b){const d=a.split(":");let c=0;for(let e=0;e<d.length;e++)a=d[e],0<=a.indexOf("[]")&&(a=a.substring(0,a.length-2))&&(b[c]=!0),a&&(d[c++]=a);c<d.length&&(d.length=c);return 1<c?d:d[0]}function ra(a,b){if(E(b))a=a[b];else for(let d=0;a&&d<b.length;d++)a=a[b[d]];return a}
+function V(a,b,d,c,e){a=a[e];if(c===d.length-1)b[e]=a;else if(a)if(a.constructor===Array)for(b=b[e]=Array(a.length),e=0;e<a.length;e++)V(a,b,d,c,e);else b=b[e]||(b[e]=A()),e=d[++c],V(a,b,d,c,e)}function W(a,b,d,c,e,f,g,h){a=a[g];if(c===b.length-1){if(a.constructor===Array){if(d[c]){for(b=0;b<a.length;b++)e.add(f,a[b],!0);return}a=a.join(" ")}e.add(f,a,h)}else if(a)if(a.constructor===Array)for(g=0;g<a.length;g++)W(a,b,d,c,e,f,g,h);else g=b[++c],W(a,b,d,c,e,f,g,h)}t=T.prototype;
+t.add=function(a,b,d){G(a)&&(b=a,a=ra(b,this.key));if(b&&(a||0===a)){if(this.register[a])return this.update(a,b);for(let c=0,e,f;c<this.g.length;c++)f=this.g[c],e=this.G[c],E(e)&&(e=[e]),W(b,e,this.u,0,this.j[f],a,e[0],d);if(this.C){let c=ra(b,this.C),e=A();E(c)&&(c=[c]);for(let f=0,g,h;f<c.length;f++)if(g=c[f],!e[g]&&(e[g]=1,h=this.h[g]||(this.h[g]=[]),!d||-1===h.indexOf(a)))if(h[h.length]=a,this.i){const k=this.register[a]||(this.register[a]=[]);k[k.length]=h}}if(this.store){let c;if(this.A){c=
+A();for(let e=0,f;e<this.A.length;e++)f=this.A[e],E(f)?c[f]=b[f]:V(b,c,f,0,f[0])}this.store[a]=c||b}}return this};t.append=function(a,b){return this.add(a,b,!0)};t.update=function(a,b){return this.remove(a).add(a,b)};
+t.remove=function(a){G(a)&&(a=a[this.key]);if(this.register[a]){for(var b=0;b<this.g.length&&(this.j[this.g[b]].remove(a,!0),!this.i||this.m);b++);if(this.C&&(!this.i||this.m))for(let d in this.h){b=this.h[d];const c=b.indexOf(a);-1!==c&&(1<b.length?b.splice(c,1):delete this.h[d])}this.store&&delete this.store[a];delete this.register[a]}return this};
+t.search=function(a,b,d){const c=this;return aa(function*(){G(a)?(d=a,a=d.query):G(b)&&(d=b,b=0);let e=[];var f=[],g;let h;let k,l,r,q,u=0;if(d)if(d.constructor===Array){var m=d;d=null}else if(m=(g=d.pluck)||d.field||d.doc,l=d.tag,h=c.store&&d.enrich,r="and"===d.bool,b=d.limit||100,q=d.offset||0,m&&(E(m)?m=[m]:m.constructor!==Array&&(k=m,m=Object.keys(m))),l&&(E(l)&&(l=[l]),!a)){for(let w=0,n;w<l.length;w++){f=l[w];if((m=(g=c.h[f])&&g.length-q)&&0<m){if(m>b||q)g=g.slice(q,q+b);h&&(g=sa.call(c,g));
+n={tag:f,result:g}}else n=void 0;n&&(e[e.length]=n,u++)}return u?e:[]}m||(m=c.g);r=r&&(1<m.length||l&&1<l.length);let x=[];if(c.m||c.async){for(let w=0,n;w<m.length;w++){var p=void 0;n=m[w];E(n)?k&&(p=k[n]):(p=n,n=n.field);x[w]=c.j[n].searchAsync(a,b,p||d)}x=yield Promise.all(x)}for(let w=0,n,B,K;w<m.length;w++){let X;B=m[w];E(B)?k&&(X=k[B]):(X=B,B=B.field);n=c.m||c.async?x[w]:c.j[B].search(a,b,X||d);K=n.length;if(l&&K){var z=[];p=0;r&&(z[0]=[n]);for(let F=0,L,C;F<l.length;F++)if(L=l[F],K=(C=c.h[L])&&
+C.length)p++,z[z.length]=r?[C]:C;if(p){if(r)p=ka(z,b||100,q||0);else{p=n;const F=A(),L=A(),C=[];for(let D=0;D<p.length;D++)F[p[D]]=1;for(let D=0,Y;D<z.length;D++){Y=z[D];for(let Z=0,M;Z<Y.length;Z++)M=Y[Z],F[M]&&!L[M]&&(L[M]=1,C[C.length]=M)}p=C}n=p;K=n.length}}if(K)f[u]=B,e[u++]=n;else if(r)return[]}if(!u)return[];if(g&&(!h||!c.store))return e[0];for(let w=0,n;w<f.length;w++){n=e[w];n.length&&h&&(n=sa.call(c,n));if(g)return n;e[w]={field:f[w],result:n}}return e}())};
+function sa(a){const b=Array(a.length);for(let d=0,c;d<a.length;d++)c=a[d],b[d]={key:c,doc:this.store[c]};return b}t.contain=function(a){return!!this.register[a]};t.get=function(a){return this.store[a]};t.set=function(a,b){this.store[a]=b;return this};t.searchCache=la;
+t.export=function(a,b,d,c,e){e||(e=0);c||(c=0);if(c<this.g.length){const f=this.g[c],g=this.j[f];b=this;setTimeout(function(){g.export(a,b,e?f.replace(":","-"):"",c,e++)||(c++,e=1,b.export(a,b,f,c,e))})}else{let f;switch(e){case 1:d="tag";f=this.h;break;case 2:d="store";f=this.store;break;default:return}na(a,this,d,c,e,f)}};
+t.import=function(a,b){if(b)switch(E(b)&&(b=JSON.parse(b)),a){case "tag":this.h=b;break;case "reg":this.i=!1;this.register=b;for(let c=0,e;c<this.g.length;c++)e=this.j[this.g[c]],e.register=b,e.i=!1;break;case "store":this.store=b;break;default:a=a.split(".");const d=a[0];a=a[1];d&&a&&this.j[d].import(a,b)}};ja(T.prototype);window.FlexSearch={Index:O,Document:T,registerCharset:function(a,b){ia[a]=b},registerLanguage:function(a,b){ha[a]=b}};}).call(this);
diff --git a/doc/0.7.0.md b/doc/0.7.0.md
index 1af7595..2c6c012 100644
--- a/doc/0.7.0.md
+++ b/doc/0.7.0.md
@@ -364,6 +364,33 @@ const index = new Document({
 });
 ```
 
+Or when you did not like to assign field names as object keys you can also use an array of objects which haves the property "field" additionally:
+
+```js
+const index = new Document({
+    key: "id",
+    doc: [{
+        field: "title",
+        tokenize: "forward",
+        optimize: "memory",
+        resolution: 9,
+        threshold: 0
+    },{
+        field:  "content",
+        tokenize: "strict",
+        optimize: "memory",
+        resolution: 9,
+        threshold: 3,
+        minlength: 3,
+        context: {
+            depth: 1,
+            resolution: 3,
+            threshold: 0
+        }
+    }]
+});
+```
+
 Field options gets inherited when also global options was passed, e.g.:
 
 ```js
@@ -447,11 +474,21 @@ index.search(query, {
         "record:title",
         "record:content:header",
         "record:content:footer"
-    ],
+    ]
 });
 ```
 
-or also:
+Same as:
+
+```js
+index.search(query, [
+    "record:title",
+    "record:content:header",
+    "record:content:footer"
+]);
+```
+
+Using field-specific options:
 
 ```js
 index.search({ 
@@ -469,6 +506,26 @@ index.search({
 });
 ```
 
+When you did not like to assign field names as object keys then you can also use an array of objects which haves the property "field":
+
+```js
+index.search([{
+    field: "record:title",
+    query: "some query",
+    limit: 100,
+    suggest: true
+},{
+    field: "record:title",
+    query: "some other query",
+    limit: 100,
+    suggest: true
+}]);
+```
+
+One advantage here is you can perform a search through the same field with different query.
+
+> When passing field-specific options you need to provide the full configuration for each field. They get not inherited like the document descriptor.
+
 #### Complex Documents
 
 You need to follow 2 rules for your documents:
@@ -652,16 +709,22 @@ Search through a given set of fields:
 index.search(query, { field: ["title", "content"] });
 ```
 
+Same as:
+
+```js
+index.search(query, ["title", "content"]);
+```
+
 Pass custom modifiers to each field:
 
 ```js
 index.search(query, {
     field: {
-        title: {
+        "title": {
             threshold: 0,
             limit: 50
         },
-        content: {
+        "content": {
             threshold: 3,
             limit: 100,
             suggest: true
@@ -675,12 +738,12 @@ Or pass custom query to each field:
 ```js
 index.search({
     field: {
-        title: {
+        "title": {
             query: "some title",
             threshold: 0,
             limit: 50
         },
-        content: {
+        "content": {
             query: "some content",
             threshold: 3,
             limit: 100,
@@ -690,6 +753,24 @@ index.search({
 });
 ```
 
+Or as array notation along a "field" property:
+
+```js
+index.search([{
+    field: "content",
+    query: "some query",
+    limit: 100,
+    suggest: true
+},{
+    field: "content",
+    query: "some other query",
+    limit: 100,
+    suggest: true
+}]);
+```
+
+One advantage here is you can perform a search through the same field with different queries.
+
 ### New Result Set
 
 One of the few breaking changes which needs migration of your old implementation is the result set. I was thinking a long time about it and came to the conclusion, that this new structure might look weird on the first time, but also comes with some nice new capabilities.
diff --git a/package.json b/package.json
index 1e364aa..6aa9baf 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "flexsearch",
-  "version": "0.7.0-pre-alpha",
+  "version": "0.7.0-beta",
   "description": "Next-Generation full text search library with zero dependencies.",
   "homepage": "https://github.com/nextapps-de/flexsearch/",
   "author": "Thomas Wilkerling",
diff --git a/src/adapter.js b/src/adapter.js
index 8bf8f3c..80ed250 100644
--- a/src/adapter.js
+++ b/src/adapter.js
@@ -1,4 +1,5 @@
 import { promise as Promise } from "./polyfill.js";
+import { is_function, is_object } from "./common.js";
 
 let counter = 0;
 
@@ -10,13 +11,13 @@ let counter = 0;
 
 function WorkerAdapter(id, options){
 
-    if(typeof id === "object"){
+    if(is_object(id)){
 
-        options = id;
+        options = /** @type {Object} */ (id);
         id = 0;
     }
 
-    if(typeof options["encode"] === "function"){
+    if(is_function(options["encode"])){
 
         options["encode"] = options["encode"].toString();
     }
@@ -48,7 +49,7 @@ function register(key){
         const arg = args[args.length - 1];
         let callback;
 
-        if(typeof arg === "function"){
+        if(is_function(arg)){
 
             callback = arg;
             args.splice(args.length - 1, 1);
diff --git a/src/async.js b/src/async.js
index 76d219a..5dac75d 100644
--- a/src/async.js
+++ b/src/async.js
@@ -1,6 +1,7 @@
 import Index from "./index.js";
 import Document from "./document.js";
 import { promise as Promise } from "./polyfill.js";
+import { is_function, is_object } from "./common.js";
 
 export default function(prototype){
 
@@ -20,7 +21,7 @@ function register(prototype, key){
         const arg = args[args.length - 1];
         let callback;
 
-        if(typeof arg === "function"){
+        if(is_function(arg)){
 
             callback = arg;
             delete args[args.length - 1];
diff --git a/src/cache.js b/src/cache.js
index 93da948..c1f9b06 100644
--- a/src/cache.js
+++ b/src/cache.js
@@ -1,6 +1,6 @@
 import Index from "./index.js";
 import Document from "./index.js";
-import { create_object } from "./common.js";
+import { create_object, is_object } from "./common.js";
 
 /**
  * @param {boolean|number=} limit
@@ -24,7 +24,7 @@ function CacheClass(limit){
 export default CacheClass;
 
 /**
- * @param {!string} query
+ * @param {string|Object} query
  * @param {number|Object=} limit
  * @param {Object=} options
  * @this {Document|Index}
@@ -33,7 +33,7 @@ export default CacheClass;
 
 export function searchCache(query, limit, options){
 
-    if(typeof query === "object"){
+    if(is_object(query)){
 
         query = query["query"];
     }
diff --git a/src/common.js b/src/common.js
index b4dee19..9f93426 100644
--- a/src/common.js
+++ b/src/common.js
@@ -1,4 +1,7 @@
-//import FlexSearch from "./flexsearch.js";
+export function parse_option(value, default_value){
+
+    return typeof value !== "undefined" ? value : default_value;
+}
 
 /**
  * @param {!Object} obj
@@ -52,4 +55,24 @@ export function concat(arrays){
 export function sort_by_length_down(a, b){
 
     return b.length - a.length;
-}
\ No newline at end of file
+}
+
+export function is_array(val){
+
+    return val.constructor === Array;
+}
+
+export function is_string(val){
+
+    return typeof val === "string";
+}
+
+export function is_object(val){
+
+    return typeof val === "object";
+}
+
+export function is_function(val){
+
+    return typeof val === "function";
+}
diff --git a/src/document.js b/src/document.js
index 54e011e..9659ba1 100644
--- a/src/document.js
+++ b/src/document.js
@@ -19,7 +19,7 @@ import {
 
 import Index from "./index.js";
 import Cache, { searchCache } from "./cache.js";
-import { create_object } from "./common.js";
+import { create_object, is_array, is_string, is_object, parse_option } from "./common.js";
 import apply_async from "./async.js";
 import { intersect, intersect_union } from "./intersect.js";
 import { exportDocument, importDocument } from "./serialize.js";
@@ -82,11 +82,6 @@ function Document(options){
 
 export default Document;
 
-function parse_option(value, default_value){
-
-    return typeof value !== "undefined" ? value : default_value;
-}
-
 /**
  * @this Document
  */
@@ -97,38 +92,37 @@ function parse_descriptor(options){
     let field = options["doc"];
     let field_options;
 
-    if(typeof field === "string"){
+    if(is_string(field)){
 
         field = [field];
     }
-    else if(field.constructor !== Array){
+    else if(!is_array(field)){
 
         field_options = field;
         field = Object.keys(field);
     }
 
-    for(let i = 0, key, item; i < field.length; i++){
+    for(let i = 0, key, opt; i < field.length; i++){
 
         key = field[i];
 
-        if(field_options){
+        if(!is_string(key)){
 
-            item = field_options[key];
-            item = typeof item === "object" ? Object.assign({}, options, item) : options;
+            opt = key;
+            key = key["field"];
         }
-        else{
+        else if(field_options){
 
-            item = options;
+            opt = field_options[key];
         }
 
-        if(this.worker){
+        opt = is_object(opt) ? Object.assign({}, options, opt) : options;
 
-            index[key] = new WorkerAdapter(item);
-        }
-        else{
+        index[key] = this.worker ?
 
-            index[key] = new Index(item, this.register);
-        }
+            new WorkerAdapter(opt)
+        :
+            new Index(opt, this.register);
 
         this.tree[i] = parse_tree(key, this.marker);
         this.field[i] = key;
@@ -138,7 +132,7 @@ function parse_descriptor(options){
 
         let store = options["store"];
 
-        if(typeof store === "string"){
+        if(is_string(store)){
 
             store = [store];
         }
@@ -187,7 +181,7 @@ function parse_tree(key, marker){
 
 function parse_simple(obj, tree){
 
-    if(typeof tree === "string"){
+    if(is_string(tree)){
 
         obj = obj[tree];
     }
@@ -216,7 +210,7 @@ function store_value(obj, store, tree, pos, key){
     }
     else if(obj){
 
-        if(obj.constructor === Array){
+        if(is_array(obj)){
 
             store = store[key] = new Array(obj.length);
 
@@ -246,7 +240,7 @@ function add_index(obj, tree, marker, pos, index, id, key, _append){
 
         // handle target value
 
-        if(obj.constructor === Array){
+        if(is_array(obj)){
 
             if(marker[pos]){
 
@@ -265,7 +259,7 @@ function add_index(obj, tree, marker, pos, index, id, key, _append){
     }
     else if(obj){
 
-        if(obj.constructor === Array){
+        if(is_array(obj)){
 
             for(let i = 0; i < obj.length; i++){
 
@@ -292,7 +286,7 @@ function add_index(obj, tree, marker, pos, index, id, key, _append){
 
 Document.prototype.add = function(id, content, _append){
 
-    if(typeof id === "object"){
+    if(is_object(id)){
 
         content = id;
         id = parse_simple(content, this.key);
@@ -310,7 +304,7 @@ Document.prototype.add = function(id, content, _append){
             field = this.field[i];
             tree = this.tree[i];
 
-            if(typeof tree === "string"){
+            if(is_string(tree)){
 
                 tree = [tree];
             }
@@ -323,7 +317,7 @@ Document.prototype.add = function(id, content, _append){
             let tag = parse_simple(content, this.tag);
             let dupes = create_object();
 
-            if(typeof tag === "string"){
+            if(is_string(tag)){
 
                 tag = [tag];
             }
@@ -365,7 +359,7 @@ Document.prototype.add = function(id, content, _append){
 
                     tree = this.storetree[i];
 
-                    if(typeof tree === "string"){
+                    if(is_string(tree)){
 
                         store[tree] = content[tree];
                     }
@@ -396,7 +390,7 @@ Document.prototype.update = function(id, content){
 
 Document.prototype.remove = function(id){
 
-    if(typeof id === "object"){
+    if(is_object(id)){
 
         id = id[this.key];
     }
@@ -407,7 +401,9 @@ Document.prototype.remove = function(id){
 
             this.index[this.field[i]].remove(id, true);
 
-            if(this.fastupdate){
+            // workers does not share the register
+
+            if(this.fastupdate && !this.worker){
 
                 // when fastupdate was enabled all ids will
                 // be already cleanup after the first loop
@@ -421,7 +417,7 @@ Document.prototype.remove = function(id){
             // when fastupdate was enabled the id will
             // be already cleanup by the index
 
-            if(!this.fastupdate){
+            if(!this.fastupdate || this.worker){
 
                 for(let key in this.tagindex){
 
@@ -456,14 +452,15 @@ Document.prototype.remove = function(id){
 
 Document.prototype.search = async function(query, limit, options){
 
-    if(typeof query === "object"){
+    if(is_object(query)){
 
         options = query;
         query = options["query"];
     }
-    else if(typeof limit === "object"){
+    else if(is_object(limit)){
 
         options = limit;
+        limit = 0;
     }
 
     let result = [], result_field = [];
@@ -472,51 +469,64 @@ Document.prototype.search = async function(query, limit, options){
 
     if(options){
 
-        pluck = options["pluck"];
-        field = pluck || options["field"];
-        tag = SUPPORT_TAGS && options["tag"];
-        enrich = SUPPORT_STORE && this.store && options["enrich"];
-        bool = options["bool"] === "and";
-        limit = options["limit"];
-        offset = options["offset"];
+        if(is_array(options)){
 
-        if(field){
-
-            if(typeof field === "string"){
-
-                field = [field];
-            }
-            else if(field.constructor !== Array){
-
-                field_options = field;
-                field = Object.keys(field);
-            }
+            field = options;
+            options = null;
         }
+        // else if(is_string(options)){
+        //
+        //     field = [options];
+        //     options = null;
+        // }
+        else{
 
-        if(tag){
+            pluck = options["pluck"];
+            field = pluck || options["field"] || options["doc"];
+            tag = SUPPORT_TAGS && options["tag"];
+            enrich = SUPPORT_STORE && this.store && options["enrich"];
+            bool = options["bool"] === "and";
+            limit = options["limit"] || 100;
+            offset = options["offset"] || 0;
 
-            if(typeof tag === "string"){
+            if(field){
 
-                tag = [tag];
+                if(is_string(field)){
+
+                    field = [field];
+                }
+                else if(!is_array(field)){
+
+                    field_options = field;
+                    field = Object.keys(field);
+                }
             }
 
-            // when tags is used and no query was set,
-            // then just return the tag indexes
+            if(tag){
 
-            if(!query){
+                if(is_string(tag)){
 
-                for(let i = 0, res; i < tag.length; i++){
-
-                    res = get_tag.call(this, tag[i], limit || 100, offset || 0, enrich);
-
-                    if(res){
-
-                        result[result.length] = res;
-                        count++;
-                    }
+                    tag = [tag];
                 }
 
-                return count ? result : [];
+                // when tags is used and no query was set,
+                // then just return the tag indexes
+
+                if(!query){
+
+                    for(let i = 0, res; i < tag.length; i++){
+
+                        res = get_tag.call(this, tag[i], limit, offset, enrich);
+
+                        if(res){
+
+                            result[result.length] = res;
+                            count++;
+                        }
+                    }
+
+                    return count ? result : [];
+                }
             }
         }
     }
@@ -532,8 +542,21 @@ Document.prototype.search = async function(query, limit, options){
 
         for(let i = 0, key; i < field.length; i++){
 
+            let opt;
+
             key = field[i];
-            async_res[i] = this.index[key][this.async ? "searchAsync" : "search"](query, limit, field_options ? field_options[key] : options);
+
+            if(!is_string(key)){
+
+                opt = key;
+                key = key["field"];
+            }
+            else if(field_options){
+
+                opt = field_options[key];
+            }
+
+            async_res[i] = this.index[key].searchAsync(query, limit, opt || options);
         }
 
         async_res = await Promise.all(async_res);
@@ -543,8 +566,20 @@ Document.prototype.search = async function(query, limit, options){
 
     for(let i = 0, res, key, len; i < field.length; i++){
 
+        let opt;
+
         key = field[i];
 
+        if(!is_string(key)){
+
+            opt = key;
+            key = key["field"];
+        }
+        else if(field_options){
+
+            opt = field_options[key];
+        }
+
         if(this.worker || this.async){
 
             res = async_res[i];
@@ -553,7 +588,7 @@ Document.prototype.search = async function(query, limit, options){
 
             // inherit options also when search? it is just for laziness, Object.assign() has a cost
 
-            res = this.index[key].search(query, limit, field_options ? field_options[key] : options);
+            res = this.index[key].search(query, limit, opt || options);
         }
 
         len = res.length;
@@ -725,13 +760,13 @@ if(SUPPORT_CACHE){
     Document.prototype.searchCache = searchCache;
 }
 
-if(SUPPORT_ASYNC){
-
-    apply_async(Document.prototype);
-}
-
 if(SUPPORT_SERIALIZE){
 
     Document.prototype.export = exportDocument;
     Document.prototype.import = importDocument;
 }
+
+if(SUPPORT_ASYNC){
+
+    apply_async(Document.prototype);
+}
diff --git a/src/engine.js b/src/engine.js
index 933e263..cc70df9 100644
--- a/src/engine.js
+++ b/src/engine.js
@@ -12,7 +12,8 @@ function Engine(index){
 
     if(DEBUG){
 
-        if(this.constructor === Engine){
+        //if(this.constructor === Engine){
+        if(this instanceof Engine){
 
             throw new Error("Can't instantiate abstract class!");
         }
diff --git a/src/index.js b/src/index.js
index f397843..1b52f0d 100644
--- a/src/index.js
+++ b/src/index.js
@@ -17,7 +17,7 @@ import {
 } from "./config.js";
 
 import { encode as default_encoder } from "./lang/latin/default.js";
-import { create_object, create_object_array, concat, sort_by_length_down } from "./common.js";
+import { create_object, create_object_array, concat, sort_by_length_down, is_array, is_string, is_object, parse_option } from "./common.js";
 import { pipeline, init_stemmer_or_matcher, init_filter } from "./lang.js";
 import { global_lang, global_charset } from "./global.js";
 import apply_async from "./async.js";
@@ -52,7 +52,7 @@ function Index(options, _register){
         charset = options["charset"];
         lang = options["lang"];
 
-        if(typeof charset === "string"){
+        if(is_string(charset)){
 
             if(charset.indexOf(":") === -1){
 
@@ -62,7 +62,7 @@ function Index(options, _register){
             charset = global_charset[charset];
         }
 
-        if(typeof lang === "string"){
+        if(is_string(lang)){
 
             lang = global_lang[lang];
         }
@@ -122,11 +122,6 @@ function Index(options, _register){
 
 export default Index;
 
-function parse_option(value, default_value){
-
-    return typeof value !== "undefined" ? value : default_value;
-}
-
 Index.prototype.pipeline = pipeline;
 
 /**
@@ -355,7 +350,7 @@ Index.prototype.push_index = function(dupes, value, score, id, append, keyword){
 }
 
 /**
- * @param {!string|Object} query
+ * @param {string|Object} query
  * @param {number|Object=} limit
  * @param {Object=} options
  * @returns {Array<number|string>}
@@ -363,14 +358,14 @@ Index.prototype.push_index = function(dupes, value, score, id, append, keyword){
 
 Index.prototype.search = function(query, limit, options){
 
-    if(typeof query === "object"){
+    if(is_object(query)){
 
-        options = query;
+        options = /** @type {Object} */ (query);
         query = options["query"];
     }
-    else if(typeof limit === "object"){
+    else if(is_object(limit)){
 
-        options = limit;
+        options = /** @type {Object} */ (limit);
     }
 
     let result = [];
@@ -697,7 +692,7 @@ function remove_index(map, id, res, optimize, resolution){
 
     let count = 0;
 
-    if(map.constructor === Array){
+    if(is_array(map)){
 
         // the first array is the score array in both strategies
 
@@ -763,13 +758,13 @@ if(SUPPORT_CACHE){
     Index.prototype.searchCache = searchCache;
 }
 
-if(SUPPORT_ASYNC){
-
-    apply_async(Index.prototype);
-}
-
 if(SUPPORT_SERIALIZE){
 
     Index.prototype.export = exportIndex;
     Index.prototype.import = importIndex;
-}
\ No newline at end of file
+}
+
+if(SUPPORT_ASYNC){
+
+    apply_async(Index.prototype);
+}
diff --git a/src/presets.js b/src/presets.js
index 345842c..c39f5dc 100644
--- a/src/presets.js
+++ b/src/presets.js
@@ -1,4 +1,5 @@
 import { DEBUG } from "./config.js";
+import { is_string } from "./common.js";
 
 /**
  * @enum {Object}
@@ -67,7 +68,7 @@ const presets = {
 
 export default function apply_preset(options){
 
-    if(typeof options === "string"){
+    if(is_string(options)){
 
         if(DEBUG && !presets[options]){
 
diff --git a/src/serialize.js b/src/serialize.js
index b300252..33d20db 100644
--- a/src/serialize.js
+++ b/src/serialize.js
@@ -1,6 +1,6 @@
 import Index from "./index.js";
 import Document from "./document.js";
-import { create_object } from "./common.js";
+import { create_object, is_string } from "./common.js";
 
 function async(callback, self, key, index_doc, index, data){
 
@@ -99,7 +99,7 @@ export function importIndex(key, data){
         return;
     }
 
-    if(typeof data === "string"){
+    if(is_string(data)){
 
         data = JSON.parse(data);
     }
@@ -202,7 +202,7 @@ export function importDocument(key, data){
         return;
     }
 
-    if(typeof data === "string"){
+    if(is_string(data)){
 
         data = JSON.parse(data);
     }
diff --git a/src/worker.js b/src/worker.js
index 11f5254..0d22601 100644
--- a/src/worker.js
+++ b/src/worker.js
@@ -1,23 +1,26 @@
 import Index from "./index.js";
+import { is_string, is_object } from "./common.js";
 
 let index, id;
 
 onmessage = function(event) {
 
     const data = event.data;
+    const args = data["args"];
 
     switch(data["task"]){
 
         case "create":
 
             const options = data["options"] || {};
+            const encode = options["encode"];
 
             options["cache"] = false;
             id = data["id"];
 
-            if(typeof options["encode"] === "string"){
+            if(is_string(encode)){
 
-                options["encode"] = Function(options["encode"]);
+                options["encode"] = new Function("return " + encode)();
             }
 
             index = new Index(options);
@@ -25,29 +28,29 @@ onmessage = function(event) {
 
         case "add":
 
-            index.add.apply(index, data["args"]);
+            index.add.apply(index, args);
             break;
 
         case "append":
 
-            index.append.apply(index, data["args"]);
+            index.append.apply(index, args);
             break;
 
         case "search":
 
-            const results = index.search.apply(index, data["args"]);
+            const results = index.search.apply(index, args);
             //postMessage({ id: id, results: results });
             postMessage(results);
             break;
 
         case "update":
 
-            index.update.apply(index, data["args"]);
+            index.update.apply(index, args);
             break;
 
         case "remove":
 
-            index.remove.apply(index, data["args"]);
+            index.remove.apply(index, args);
             break;
     }
 };