Javascript | Javascript kata |Node JS | Data Types | Variables | Control Flow | Scope and Environment | Objects | Functions | Events | Prototypal Inheritance | Three.js | 3DE Code Editor |

Javascript Data Types

There are 8 fundamental data types:

• Numbers, Strings, Booleans, Objects, Functions, Undefined, Bigints, Symbols

Variables don’t have types. The values have types. remember to use typeof operator.

1. Numbers

5 0b101 0o5 0x5 5e7

1. ```
10 * "string" => NaN
10/0 => Infinity
-10/0 => -Infinity

1. Strings
2. `"" ’’ ```

let s = “Jane is good” s.length //12 s.toLowerCase() s.toUpperCase()

1. ## Booleans
1. ```
true
false

"" 0 NaN 0n // Bigint value null undefined false

1. ## Objects
1. ```
let person ={
 name: "Jane",  // don't forget the commas!
 age: 5
}
person.name;
person["name"];
person.age = 6;
let newPerson = person;

newPerson.age = 7; person.age; // 7

1. `newPerson`
1. `person`
1. ```
let name = "Jane";
let age = 8;
let oldPerson = {
  name,
  age,
 }

let somePerson = null; typeof somePerson; // ‘object’

1. ### Arrays
1. ```
let a = [0, 1];  // undefined
a.length;
a[0] = 2;
a.push(3);
a.pop();
a.unshift(4)
a.shift().
a.indexOf(1);

map filter sort

1. ## Functions
1. ```
 function add(x, y){
    return x+y;
 }

let add1 = function(x, y){ return x+y; }

1. ```
let add2 = (x, y) => {
    return x+y;
 }

1. Undefined

typeof blah; //undefined let x; //undefined blah.x //undefined blah[0] //undefined typeof undefined; // undefined typeof null; // object

1. ## Bigints
1. ` 10n `
1. ```
  10n + BigInt(2) // 12n

1. Symbols

2.  let mySym = Symbol("aGoodSymbol");
    mySym;                             // Symbol(aGoodSymbol)
    let mySym1 = Symbol.for("aVeryGoodSymbol");