Javascript has seven types that are divided into two categories: primitive and no-primitive.
The primitive includes numbers, string, boolean, undefined, null, and non-primitive includes object and symbol.
The 'symbol' data type is new in JS. It has been included in the ES6 version.
JavaScript Numbers
Numbers represent integer and floating numbers (decimal and exponentials). For example
const number1 = 3;
const number2 = 3.433;
const number3 = 3e5 // 3 * 10^5
A number type can also be +Infinity, - Infinity and NaN
Javascript String
String is used to store text. In JS, string are surrounded by quotes.
Example: "hello", 'hello', `hello`.
Javascript Boolean
Boolean represents two values: true or false.
const isChecked = true;
const isOpen = false;
Javascript Undefined
The undefined data type represents value that is not assigned. If a variable is declared but the value is not assigned, the the value of that variable will be undefined.
let name;
console.log(name) // undefined.
Javascript null
Null is a special value that represents empty or unknow value
const number = null;
Note: null is not the same as NULL or Null
Javascript Symbol.
Symbol is an immutable primitive value that is unique.
const name1 = Symbol('Adam');
const name2 = Symbol('Adam')'
name1 and name2 both contain 'Adam' but they are different as they are of the Symbol type.
Javascript Object
An Object is a complex data type that allow we to store data follow by key-value. For example:
const person = {
name: 'Adam',
age: 10,
address: 'Vietnam'
};
What is the difference between primitive and non-primitive?
Primitive is defined by value.
Non-primitive defined by reference.