JavaScript symbols
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The document explains the JavaScript primitive data type 'Symbol', which is unique and used for creating unique identifiers. Symbols cannot be seen in typical object enumeration or serialization methods, making them suitable for private properties. It provides examples of symbol creation and usage in objects.
![Symbol
It won’t be enumerated in for…in loops, and are
ignored by functions such as JSON.stringify(),
Object.keys() and Object.getOwnPropertyNames().
This makes them ideal for properties that you
don’t want to be included when serializing an
object.
const user = {};
const email = Symbol();
user.name = 'Elon';
user.age = 48;
user[email] = 'elon@tesla.com';
Object.keys(user);
// [ "name", "age" ]
JSON.stringify(user);
// "{"name":"Elon","age":48}"](https://image.slidesharecdn.com/zurcddjpsqigll6geeo4-signature-6b19ea6f59b552a7f2bf377c4348828be1efdc6298525958dec5884fee353cc4-poli-200616031651/85/JavaScript-symbols-4-320.jpg)
JavaScript symbols
- 2. Symbol It is a primitive data type along with string, number, boolean, null and undefined. To create a new primitive symbol, you define it with the following syntax. let mySymbol = Symbol(); You can pass a parameter to Symbol(), and that is used as the symbol description, useful just for debugging purposes. let mySecondSymbol = Symbol('orange');
- 3. Symbol They are unique, and every time you invoke Symbol(), you get a new and unique symbol which is guaranteed to be different from all other symbols. You can see it here, Symbol() === Symbol() //false Symbol('orange') === Symbol('orange') // false console.log(Symbol()); //Symbol() console.log(Symbol('orange')); //Symbol(orange) Even though every symbol gives a unique value we can’t view them by logging.
- 4. Symbol It won’t be enumerated in for…in loops, and are ignored by functions such as JSON.stringify(), Object.keys() and Object.getOwnPropertyNames(). This makes them ideal for properties that you don’t want to be included when serializing an object. const user = {}; const email = Symbol(); user.name = 'Elon'; user.age = 48; user[email] = 'elon@tesla.com'; Object.keys(user); // [ "name", "age" ] JSON.stringify(user); // "{"name":"Elon","age":48}"
- 5. Let’s say you created a user object as shown in the previous slide and have an object like, What are the ways you can retrieve the value “elon@tesla.com” from the user object? Comment your answers below 👇 {name: "Elon", age: 48, Symbol(): "elon@tesla.com"} 💡Question for you: