JavaScript has 6 data types:
Numbers are any number without quotes, including numbers with decimals.
For example: -10, 258, 3.14.
Strings are characters wrapped in single or double quotes.
Example:
let str = "Hello World";
undefined represents a lack of defined value.
Variables declared but not initialized to a value will have the value undefined.
let x;
console.log(typeof x); // undefined
null represents the intentional absence of a value. So it’s empty, and there’s nothing in it.
const x = null;
Boolean has 2 values: true or false.
In Javascript, 0, empty strings, undefined, null, and NaN (Not-A-Number) are all considered false values.
const isGood = true;
An object is the collection of related data.
let dog = {
name: "Puppy",
age: 2,
color: "gray",
};
name, age, and color are the properties of the dog object. We access the values of these properties using the dot or bracket notation.
// Using dot
console.log(dog.name); // Puppy
// Using bracket
console.log(dog["age"]); // 2