diff --git a/src/NodeUtils.js b/src/NodeUtils.js
index f8a9eda4..f8fb28d6 100644
--- a/src/NodeUtils.js
+++ b/src/NodeUtils.js
@@ -1,5 +1,4 @@
 "use strict";
-let estraverse = require('estraverse');
 class NodeUtils {
     static getNodeScope(node, deep = 0) {
         let scopeNodes = [
diff --git a/src/NodeUtils.ts b/src/NodeUtils.ts
index 253994ef..3310695f 100644
--- a/src/NodeUtils.ts
+++ b/src/NodeUtils.ts
@@ -1,5 +1,3 @@
-let estraverse = require('estraverse');
-
 export class NodeUtils {
     /**
      * @param node
diff --git a/src/node-obfuscators/CatchClauseObfuscator.js b/src/node-obfuscators/CatchClauseObfuscator.js
index 2cf3c45b..8e09a330 100644
--- a/src/node-obfuscators/CatchClauseObfuscator.js
+++ b/src/node-obfuscators/CatchClauseObfuscator.js
@@ -1,7 +1,7 @@
 "use strict";
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
 const Utils_1 = require('../Utils');
-let estraverse = require('estraverse');
 class CatchClauseObfuscator extends NodeObfuscator_1.NodeObfuscator {
     constructor(...args) {
         super(...args);
diff --git a/src/node-obfuscators/CatchClauseObfuscator.ts b/src/node-obfuscators/CatchClauseObfuscator.ts
index 90275b01..76247283 100644
--- a/src/node-obfuscators/CatchClauseObfuscator.ts
+++ b/src/node-obfuscators/CatchClauseObfuscator.ts
@@ -1,8 +1,8 @@
+import * as estraverse from 'estraverse';
+
 import { NodeObfuscator } from './NodeObfuscator';
 import { Utils } from '../Utils';
 
-let estraverse = require('estraverse');
-
 /**
  * replaces:
  *     try {} catch (e) { console.log(e); };
diff --git a/src/node-obfuscators/FunctionDeclarationObfuscator.js b/src/node-obfuscators/FunctionDeclarationObfuscator.js
index 0329bc0e..94353df3 100644
--- a/src/node-obfuscators/FunctionDeclarationObfuscator.js
+++ b/src/node-obfuscators/FunctionDeclarationObfuscator.js
@@ -1,8 +1,8 @@
 "use strict";
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
 const NodeUtils_1 = require("../NodeUtils");
 const Utils_1 = require('../Utils');
-let estraverse = require('estraverse');
 class FunctionDeclarationObfuscator extends NodeObfuscator_1.NodeObfuscator {
     constructor(...args) {
         super(...args);
diff --git a/src/node-obfuscators/FunctionDeclarationObfuscator.ts b/src/node-obfuscators/FunctionDeclarationObfuscator.ts
index a118a048..96ab2703 100644
--- a/src/node-obfuscators/FunctionDeclarationObfuscator.ts
+++ b/src/node-obfuscators/FunctionDeclarationObfuscator.ts
@@ -1,9 +1,9 @@
+import * as estraverse from 'estraverse';
+
 import { NodeObfuscator } from './NodeObfuscator';
 import { NodeUtils } from "../NodeUtils";
 import { Utils } from '../Utils';
 
-let estraverse = require('estraverse');
-
 /**
  * replaces:
  *     function foo () { //... };
diff --git a/src/node-obfuscators/FunctionObfuscator.js b/src/node-obfuscators/FunctionObfuscator.js
index 0da2f817..e7c29134 100644
--- a/src/node-obfuscators/FunctionObfuscator.js
+++ b/src/node-obfuscators/FunctionObfuscator.js
@@ -1,7 +1,7 @@
 "use strict";
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
 const Utils_1 = require('../Utils');
-let estraverse = require('estraverse');
 class FunctionObfuscator extends NodeObfuscator_1.NodeObfuscator {
     constructor(...args) {
         super(...args);
diff --git a/src/node-obfuscators/FunctionObfuscator.ts b/src/node-obfuscators/FunctionObfuscator.ts
index b79d66e6..f6fb4be2 100644
--- a/src/node-obfuscators/FunctionObfuscator.ts
+++ b/src/node-obfuscators/FunctionObfuscator.ts
@@ -1,8 +1,8 @@
+import * as estraverse from 'estraverse';
+
 import { NodeObfuscator } from './NodeObfuscator';
 import { Utils } from '../Utils';
 
-let estraverse = require('estraverse');
-
 /**
  * replaces:
  *     function foo (argument1) { return argument1; };
diff --git a/src/node-obfuscators/LiteralObfuscator.js b/src/node-obfuscators/LiteralObfuscator.js
index c53e4bbf..0c5e6e75 100644
--- a/src/node-obfuscators/LiteralObfuscator.js
+++ b/src/node-obfuscators/LiteralObfuscator.js
@@ -1,6 +1,6 @@
 "use strict";
+const escodegen = require('escodegen');
 const NodeObfuscator_1 = require('./NodeObfuscator');
-let escodegen = require('escodegen'), estraverse = require('estraverse');
 class LiteralObfuscator extends NodeObfuscator_1.NodeObfuscator {
     obfuscateNode(literalNode, parentNode) {
         if (parentNode.type === 'Property' && parentNode.key === literalNode) {
diff --git a/src/node-obfuscators/LiteralObfuscator.ts b/src/node-obfuscators/LiteralObfuscator.ts
index 9dc904a9..238ba433 100644
--- a/src/node-obfuscators/LiteralObfuscator.ts
+++ b/src/node-obfuscators/LiteralObfuscator.ts
@@ -1,7 +1,6 @@
-import { NodeObfuscator } from './NodeObfuscator'
+import * as escodegen from 'escodegen';
 
-let escodegen = require('escodegen'),
-    estraverse = require('estraverse');
+import { NodeObfuscator } from './NodeObfuscator';
 
 export class LiteralObfuscator extends NodeObfuscator {
     /**
diff --git a/src/node-obfuscators/MemberExpressionObfuscator.js b/src/node-obfuscators/MemberExpressionObfuscator.js
index 9c5393ae..2eec264a 100644
--- a/src/node-obfuscators/MemberExpressionObfuscator.js
+++ b/src/node-obfuscators/MemberExpressionObfuscator.js
@@ -1,6 +1,7 @@
 "use strict";
+const escodegen = require('escodegen');
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
-let escodegen = require('escodegen'), estraverse = require('estraverse');
 class MemberExpressionObfuscator extends NodeObfuscator_1.NodeObfuscator {
     obfuscateNode(memberExpressionNode) {
         estraverse.replace(memberExpressionNode.property, {
@@ -27,7 +28,7 @@ class MemberExpressionObfuscator extends NodeObfuscator_1.NodeObfuscator {
         node['raw'] = `'${nodeValue}'`;
         node['x-verbatim-property'] = {
             content: this.replaceLiteralStringByArrayElement(nodeValue),
-            precedence: escodegen['Precedence']['Primary']
+            precedence: escodegen.Precedence.Primary
         };
         delete node['name'];
     }
@@ -39,7 +40,7 @@ class MemberExpressionObfuscator extends NodeObfuscator_1.NodeObfuscator {
                 }
                 node['x-verbatim-property'] = {
                     content: this.replaceLiteralStringByArrayElement(node.value),
-                    precedence: escodegen['Precedence']['Primary']
+                    precedence: escodegen.Precedence.Primary
                 };
                 break;
         }
diff --git a/src/node-obfuscators/MemberExpressionObfuscator.ts b/src/node-obfuscators/MemberExpressionObfuscator.ts
index b392f84f..1672563b 100644
--- a/src/node-obfuscators/MemberExpressionObfuscator.ts
+++ b/src/node-obfuscators/MemberExpressionObfuscator.ts
@@ -1,7 +1,7 @@
-import { NodeObfuscator } from './NodeObfuscator'
+import * as escodegen from 'escodegen';
+import * as estraverse from 'estraverse';
 
-let escodegen = require('escodegen'),
-    estraverse = require('estraverse');
+import { NodeObfuscator } from './NodeObfuscator'
 
 export class MemberExpressionObfuscator extends NodeObfuscator {
     /**
@@ -50,7 +50,7 @@ export class MemberExpressionObfuscator extends NodeObfuscator {
         node['raw'] = `'${nodeValue}'`;
         node['x-verbatim-property'] = {
             content : this.replaceLiteralStringByArrayElement(nodeValue),
-            precedence: escodegen['Precedence']['Primary']
+            precedence: escodegen.Precedence.Primary
         };
 
         delete node['name'];
@@ -74,7 +74,7 @@ export class MemberExpressionObfuscator extends NodeObfuscator {
 
                 node['x-verbatim-property'] = {
                     content : this.replaceLiteralStringByArrayElement(node.value),
-                    precedence: escodegen['Precedence']['Primary']
+                    precedence: escodegen.Precedence.Primary
                 };
 
                 break;
diff --git a/src/node-obfuscators/MethodDefinitionObfuscator.js b/src/node-obfuscators/MethodDefinitionObfuscator.js
index d1af1cd0..cf938ddc 100644
--- a/src/node-obfuscators/MethodDefinitionObfuscator.js
+++ b/src/node-obfuscators/MethodDefinitionObfuscator.js
@@ -1,6 +1,6 @@
 "use strict";
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
-let estraverse = require('estraverse');
 class MethodDefinitionObfuscator extends NodeObfuscator_1.NodeObfuscator {
     constructor(...args) {
         super(...args);
diff --git a/src/node-obfuscators/MethodDefinitionObfuscator.ts b/src/node-obfuscators/MethodDefinitionObfuscator.ts
index 1bca6507..787cfe7d 100644
--- a/src/node-obfuscators/MethodDefinitionObfuscator.ts
+++ b/src/node-obfuscators/MethodDefinitionObfuscator.ts
@@ -1,7 +1,6 @@
-import { NodeObfuscator } from './NodeObfuscator';
-import { Utils } from '../Utils';
+import * as estraverse from 'estraverse';
 
-let estraverse = require('estraverse');
+import { NodeObfuscator } from './NodeObfuscator';
 
 /**
  * replaces:
diff --git a/src/node-obfuscators/NodeObfuscator.ts b/src/node-obfuscators/NodeObfuscator.ts
index b73af8c2..2d0723d2 100644
--- a/src/node-obfuscators/NodeObfuscator.ts
+++ b/src/node-obfuscators/NodeObfuscator.ts
@@ -1,7 +1,6 @@
 import { INode } from '../interfaces/INode';
 import { INodeObfuscator } from '../interfaces/INodeObfuscator';
 
-import { UnicodeArrayNode } from '../nodes/UnicodeArrayNode';
 import { Utils } from '../Utils';
 
 export abstract class NodeObfuscator implements INodeObfuscator {
diff --git a/src/node-obfuscators/ObjectExpressionObfuscator.js b/src/node-obfuscators/ObjectExpressionObfuscator.js
index e07b3416..9713c081 100644
--- a/src/node-obfuscators/ObjectExpressionObfuscator.js
+++ b/src/node-obfuscators/ObjectExpressionObfuscator.js
@@ -1,7 +1,8 @@
 "use strict";
+const escodegen = require('escodegen');
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
 const Utils_1 = require('../Utils');
-let escodegen = require('escodegen'), estraverse = require('estraverse');
 class ObjectExpressionObfuscator extends NodeObfuscator_1.NodeObfuscator {
     obfuscateNode(objectExpressionNode) {
         objectExpressionNode.properties.forEach((property) => {
@@ -27,7 +28,7 @@ class ObjectExpressionObfuscator extends NodeObfuscator_1.NodeObfuscator {
                 }
                 node['x-verbatim-property'] = {
                     content: Utils_1.Utils.stringToUnicode(node.value),
-                    precedence: escodegen['Precedence']['Primary']
+                    precedence: escodegen.Precedence.Primary
                 };
                 break;
         }
diff --git a/src/node-obfuscators/ObjectExpressionObfuscator.ts b/src/node-obfuscators/ObjectExpressionObfuscator.ts
index 4a798c2a..60f4c951 100644
--- a/src/node-obfuscators/ObjectExpressionObfuscator.ts
+++ b/src/node-obfuscators/ObjectExpressionObfuscator.ts
@@ -1,9 +1,9 @@
+import * as escodegen from 'escodegen';
+import * as estraverse from 'estraverse';
+
 import { NodeObfuscator } from './NodeObfuscator'
 import { Utils } from '../Utils';
 
-let escodegen = require('escodegen'),
-    estraverse = require('estraverse');
-
 /**
  * replaces:
  *     var object = { 'PSEUDO': 1 };
@@ -50,7 +50,7 @@ export class ObjectExpressionObfuscator extends NodeObfuscator {
 
                 node['x-verbatim-property'] = {
                     content : Utils.stringToUnicode(node.value),
-                    precedence: escodegen['Precedence']['Primary']
+                    precedence: escodegen.Precedence.Primary
                 };
 
                 break;
diff --git a/src/node-obfuscators/VariableDeclarationObfuscator.js b/src/node-obfuscators/VariableDeclarationObfuscator.js
index 4bac5db8..7c73e28b 100644
--- a/src/node-obfuscators/VariableDeclarationObfuscator.js
+++ b/src/node-obfuscators/VariableDeclarationObfuscator.js
@@ -1,8 +1,8 @@
 "use strict";
+const estraverse = require('estraverse');
 const NodeObfuscator_1 = require('./NodeObfuscator');
 const NodeUtils_1 = require("../NodeUtils");
 const Utils_1 = require('../Utils');
-let estraverse = require('estraverse');
 class VariableDeclarationObfuscator extends NodeObfuscator_1.NodeObfuscator {
     constructor(...args) {
         super(...args);
diff --git a/src/node-obfuscators/VariableDeclarationObfuscator.ts b/src/node-obfuscators/VariableDeclarationObfuscator.ts
index a8254d88..55f792cb 100644
--- a/src/node-obfuscators/VariableDeclarationObfuscator.ts
+++ b/src/node-obfuscators/VariableDeclarationObfuscator.ts
@@ -1,9 +1,9 @@
+import * as estraverse from 'estraverse';
+
 import { NodeObfuscator } from './NodeObfuscator';
 import { NodeUtils } from "../NodeUtils";
 import { Utils } from '../Utils';
 
-let estraverse = require('estraverse');
-
 /**
  * replaces:
  *     var variable = 1;
diff --git a/src/nodes/UnicodeArrayNode.js b/src/nodes/UnicodeArrayNode.js
index 485f8cd3..4b5d890c 100644
--- a/src/nodes/UnicodeArrayNode.js
+++ b/src/nodes/UnicodeArrayNode.js
@@ -1,8 +1,9 @@
 "use strict";
+const escodegen = require('escodegen');
+const estraverse = require('estraverse');
 const Node_1 = require('./Node');
 const Utils_1 = require('../Utils');
 const AppendState_1 = require('../enums/AppendState');
-let escodegen = require('escodegen'), estraverse = require('estraverse');
 class UnicodeArrayNode extends Node_1.Node {
     constructor(astTree, unicodeArrayName, unicodeArrayRotateValue = 0) {
         super();
diff --git a/src/nodes/UnicodeArrayNode.ts b/src/nodes/UnicodeArrayNode.ts
index 823bf1be..e072bf96 100644
--- a/src/nodes/UnicodeArrayNode.ts
+++ b/src/nodes/UnicodeArrayNode.ts
@@ -1,11 +1,11 @@
+import * as escodegen from 'escodegen';
+import * as estraverse from 'estraverse';
+
 import { Node } from './Node';
 import { Utils } from '../Utils';
 
 import { AppendState } from '../enums/AppendState';
 
-let escodegen = require('escodegen'),
-    estraverse = require('estraverse');
-
 export class UnicodeArrayNode extends Node {
     /**
      * @type {number}
diff --git a/src/nodes/UnicodeArrayRotateFunctionCallNode.js b/src/nodes/UnicodeArrayRotateFunctionCallNode.js
index 7deb497a..93331686 100644
--- a/src/nodes/UnicodeArrayRotateFunctionCallNode.js
+++ b/src/nodes/UnicodeArrayRotateFunctionCallNode.js
@@ -1,6 +1,6 @@
 "use strict";
+const estraverse = require('estraverse');
 const Node_1 = require('./Node');
-let estraverse = require('estraverse');
 class UnicodeArrayRotateFunctionCallNode extends Node_1.Node {
     constructor(astTree, unicodeArrayRotateFunctionName, unicodeArrayName, unicodeArrayRotateValue) {
         super();
diff --git a/src/nodes/UnicodeArrayRotateFunctionCallNode.ts b/src/nodes/UnicodeArrayRotateFunctionCallNode.ts
index 7577144b..cfba85a1 100644
--- a/src/nodes/UnicodeArrayRotateFunctionCallNode.ts
+++ b/src/nodes/UnicodeArrayRotateFunctionCallNode.ts
@@ -1,6 +1,6 @@
-import { Node } from './Node';
+import * as estraverse from 'estraverse';
 
-let estraverse = require('estraverse');
+import { Node } from './Node';
 
 export class UnicodeArrayRotateFunctionCallNode extends Node {
     /**
diff --git a/src/nodes/UnicodeArrayRotateFunctionNode.js b/src/nodes/UnicodeArrayRotateFunctionNode.js
index f8e0e273..792df0f6 100644
--- a/src/nodes/UnicodeArrayRotateFunctionNode.js
+++ b/src/nodes/UnicodeArrayRotateFunctionNode.js
@@ -1,7 +1,7 @@
 "use strict";
+const estraverse = require('estraverse');
 const Node_1 = require('./Node');
 const Utils_1 = require('../Utils');
-let estraverse = require('estraverse');
 class UnicodeArrayRotateFunctionNode extends Node_1.Node {
     constructor(astTree, unicodeArrayRotateFunctionName, unicodeArrayName) {
         super();
diff --git a/src/nodes/UnicodeArrayRotateFunctionNode.ts b/src/nodes/UnicodeArrayRotateFunctionNode.ts
index 68aec677..ef0a2535 100644
--- a/src/nodes/UnicodeArrayRotateFunctionNode.ts
+++ b/src/nodes/UnicodeArrayRotateFunctionNode.ts
@@ -1,8 +1,8 @@
+import * as estraverse from 'estraverse';
+
 import { Node } from './Node';
 import { Utils } from '../Utils';
 
-let estraverse = require('estraverse');
-
 export class UnicodeArrayRotateFunctionNode extends Node {
     /**
      * @type any
diff --git a/typings/custom/escodegen/escodegen.d.ts b/typings/custom/escodegen/escodegen.d.ts
index 34ce070a..617046d1 100644
--- a/typings/custom/escodegen/escodegen.d.ts
+++ b/typings/custom/escodegen/escodegen.d.ts
@@ -10,6 +10,10 @@ declare namespace escodegen {
         }
     }
 
+    enum Precedence {
+        Primary
+    }
+
     function generate(ast: any, opts?: GenerateOpts): string;
 }