ncatalin
3/10/2018 - 2:51 PM

Symbols

Modern JavaScript From The Beginning from Brad Traversy

index.html
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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>JavaScript Sandbox</title>
</head>
<body>
  
  <script src="app.js"></script>
</body>
</html>
app.js
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// Create a symbol
// const sym1 = Symbol();
// const sym2 = Symbol('sym2');

// console.log(typeof sym2);

// console.log(Symbol('123') === Symbol('123'));
// console.log(`Hello ${sym1.toString()}`);

// Unique Object Keys
const KEY1 = Symbol();
const KEY2 = Symbol('sym2');

const myObj = {};

myObj[KEY1] = 'Prop1';
myObj[KEY2] = 'Prop2';
myObj.key3 = 'Prop3';
myObj.key4 = 'Prop4';

// console.log(myObj[KEY1]);
// console.log(myObj[KEY2]);

// Symbols are not enumerable in for...in
// for(let i in myObj) {
//   console.log(`${i}: ${myObj[i]}`);
// }

// Symbols are ignored by JSON.stringify
console.log(JSON.stringify({key: 'prop'}));
console.log(JSON.stringify({[Symbol('sym1')]: 'prop'}));