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Add ES6 code samples
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‎README.md‎

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@@ -462,34 +462,34 @@ Each proposal for an ECMAScript feature goes through the following maturity stag
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You can make the object iterable by defining a `Symbol.iterator` property on it.
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```js
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const collection = {
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one: 1,
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two: 2,
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three: 3,
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[Symbol.iterator]() {
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const values = Object.keys(this);
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let i = 0;
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const collection = {
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one: 1,
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two: 2,
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three: 3,
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[Symbol.iterator]() {
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const values = Object.keys(this);
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let i = 0;
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return {
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next: () => {
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return {
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next: () => {
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return {
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value: this[values[i++]],
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done: i > values.length
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}
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}
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};
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value: this[values[i++]],
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done: i > values.length
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}
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}
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};
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}
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};
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const iterator = collection[Symbol.iterator]();
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const iterator = collection[Symbol.iterator]();
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console.log(iterator.next()); // → {value: 1, done: false}
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console.log(iterator.next()); // → {value: 2, done: false}
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console.log(iterator.next()); // → {value: 3, done: false}
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console.log(iterator.next()); // → {value: undefined, done: true}
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console.log(iterator.next()); // → {value: 1, done: false}
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console.log(iterator.next()); // → {value: 2, done: false}
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console.log(iterator.next()); // → {value: 3, done: false}
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console.log(iterator.next()); // → {value: undefined, done: true}
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for (const value of collection) {
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console.log(value);
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}
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for (const value of collection) {
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console.log(value);
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}
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```
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The for...of statement creates a loop iterating over user defined collection object. But this loop can be used for built-in objects too.
@@ -733,7 +733,7 @@ Each proposal for an ECMAScript feature goes through the following maturity stag
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console.log(String.fromCodePoint(134071)); // "𠮷"
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```
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19. ### Symbols
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18. ### Symbols
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Symbol is a new peculiar primitive data type of JavaScript, along with other primitive types such as string, number, boolean, null and undefined. The new symbol is created just by calling the Symbol function. i.e, Every time you call the Symbol function, you’ll get a new and completely unique value. You can also pass a parameter to Symbol(), which is useful for debugging purpose only.
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console.log(Symbol.for('foo') === Symbol.for('foo')); // true
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```
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18. ### Proxies
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19. ### Proxies
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The Proxy object is used to create a proxy for another object, which can intercept and redefine fundamental operations for that object such as property lookup, assignment, enumeration, function invocation etc. These are used in many libraries and some browser frameworks.
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The proxy object is created with two parameters with below syntax,
@@ -854,28 +854,28 @@ Each proposal for an ECMAScript feature goes through the following maturity stag
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The promise chaining structure would be as below,
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```js
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const promise = new Promise(function(resolve, reject) {
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setTimeout(() => resolve(1), 1000);
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});
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const promise = new Promise(function(resolve, reject) {
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setTimeout(() => resolve(1), 1000);
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});
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promise.then(function(result) {
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promise.then(function(result) {
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console.log(result); // 1
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return result * 2;
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console.log(result); // 1
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return result * 2;
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}).then(function(result) {
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}).then(function(result) {
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console.log(result); // 2
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return result * 3;
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console.log(result); // 2
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return result * 3;
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}).then(function(result) {
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}).then(function(result) {
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console.log(result); // 6
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return result * 4;
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console.log(result); // 6
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return result * 4;
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}).catch(function(error){
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console.log(error);
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});
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}).catch(function(error){
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console.log(error);
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});
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```
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21. ### Reflect
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6. **:**
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13. ### Binary and Octal
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22. ### Binary and Octal
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ES5 provided numeric literals in octal (prefix 0), decimal (no prefix), and hexadecimal ( 0x) representation. ES6 added support for binary literals and improvements on octal literals.
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**1. Binary literals:**

‎es2015/10.iterators-forof.js‎

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const collection = {
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one: 1,
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two: 2,
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three: 3,
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[Symbol.iterator]() {
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const values = Object.keys(this);
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let i = 0;
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return {
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next: () => {
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return {
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value: this[values[i++]],
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done: i > values.length
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}
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}
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};
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}
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};
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const iterator = collection[Symbol.iterator]();
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console.log(iterator.next()); // → {value: 1, done: false}
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console.log(iterator.next()); // → {value: 2, done: false}
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console.log(iterator.next()); // → {value: 3, done: false}
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console.log(iterator.next()); // → {value: undefined, done: true}
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for (const value of collection) {
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console.log(value);
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}

‎es2015/11.generators.js‎

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function* myGenerator(i) {
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yield i + 10;
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yield i + 20;
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return i + 30;
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}
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const myGenObj = myGenerator(10);
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console.log(myGenObj.next().value); // 20
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console.log(myGenObj.next().value); // 30
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console.log(myGenObj.next().value); // 40

‎es2015/12.modules.js‎

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//Export Statement
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// Named exports
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// module "my-module.js"
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const PI = Math.PI;
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function add(...args) {
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return args.reduce((num, tot) => tot + num);
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}
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function multiply(...args) {
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return args.reduce((num, tot) => tot * num);
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}
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// private function
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function print(msg) {
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console.log(msg);
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}
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export { PI, add, multiply };
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// Default exports
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// module "my-module.js"
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export default function add(...args) {
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return args.reduce((num, tot) => tot + num);
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}
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//Import Statement
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// 1. Import an entire module's contents
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import * as name from "my-module";
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//2.Import a single export from a module
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import { export1 } from "my-module";
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//3.Import multiple exports from a module
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import { export1 , export2 } from "my-module";
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//4.Import default export from a module
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import defaultExport from "my-module";
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//5.Import an export with an alias
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import { export1 as alias1 } from "my-module";
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‎es2015/17.unicode.js‎

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let str = '𠮷';
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// new string form
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console.log('\u{20BB7}'); // "𠮷"
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// new RegExp u mode
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console.log(new RegExp('\u{20BB7}', 'u'));
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console.log(/^.$/u.test(str)); // true
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//API methods
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console.log(str.codePointAt(0)); // 134071
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console.log(str.codePointAt(1)); // 57271
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console.log(String.fromCodePoint(134071)); // "𠮷"

‎es2015/18.symbols.js‎

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//1. Object properties
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let id = Symbol("id");
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let user = {
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name: "John",
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age: 40,
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[id]: 111
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};
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for (let key in user) {
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console.log(key); // name, age without symbols
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}
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console.log(JSON.stringify(user)); // {"name":"John", "age": 40}
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console.log(Object.keys(user)); // ["name", "age"]
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console.log( "User Id: " + user[id] ); // Direct access by the symbol works
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//2. Unique constants
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const logLevels = {
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DEBUG: Symbol('debug'),
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INFO: Symbol('info'),
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WARN: Symbol('warn'),
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ERROR: Symbol('error'),
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};
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console.log(logLevels.DEBUG, 'debug message');
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console.log(logLevels.INFO, 'info message');
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//3. Equality Checks
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console.log(Symbol('foo') === Symbol('foo')); // false
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console.log(Symbol.for('foo') === Symbol.for('foo')); // true

‎es2015/19.proxies.js‎

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const target = {
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name: "John",
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age: 3
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};
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const handler = {
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get: function(target, prop) {
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return prop in target ?
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target[prop] :
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`${prop} does not exist';
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}
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};
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const user = new Proxy(target, handler);
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console.log(user.name); // John
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console.log(user.age); // John
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console.log(user.gender); // gender does not exist
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// validations
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let ageValidator = {
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set: function(obj, prop, value) {
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if (prop === 'age') {
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if (!Number.isInteger(value)) {
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throw new TypeError('The age is not an integer');
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}
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if (value > 200) {
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throw new RangeError('Invalid age');
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}
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}
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obj[prop] = value; // The default behavior to store the value
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return true; // Indicate success
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}
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};
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const person = new Proxy({}, validator);
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person.age = 30;
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console.log(person.age); // 30
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person.age = 'old'; // Throws an exception
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person.age = 200; // Throws an exception

‎es2015/20.promises.js‎

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const promise = new Promise(function(resolve, reject) {
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setTimeout(() => resolve(1), 1000);
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});
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promise.then(function(result) {
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console.log(result); // 1
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return result * 2;
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}).then(function(result) {
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console.log(result); // 2
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return result * 3;
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}).then(function(result) {
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console.log(result); // 6
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return result * 4;
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}).catch(function(error){
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console.log(error);
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});

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