JavaScript object is a non-primitive data-type that allows you to store multiple collections of data.
Syntax
const object_name = {
key1: value1,
key2: value2
}
Object Declaration
We can define objects in one line also
const person = { name: 'John', age: 20 };
console.log(person);
// Output : Object { name: "John", age: 20 }
If we have multiple properties then object can be defined using this way.
const person = {
name: 'John',
age: 20
};
console.log(typeof person);
// Output : Object
Here, the student is an object that stores values such as strings and numbers. person objects have two properties name, and age with particular values john & 20 respectively. When an object has multiple properties, you use a comma (,) to separate them like in the above example.
Object Properties
In JavaScript, "key: value" pairs are called properties.
let person = {
name: 'John',
age: 20
};
In the above example, name:’john’ & age:20 are properties of an object.
Accessing Object Properties
we can access the value of a property by using its key. Properties can be accessed using dot notation and bracket notation.
Dot notation
Syntax
objectName.key
const person = {
name: 'John',
age: 20,
};
// accessing property
console.log(person.name);
// Output : John
Bracket notation
Syntax
objectName["propertyName"]
const person = {
name: 'John',
age: 20,
};
// accessing property
console.log(person["name"]);
// Output : John
Nested Objects
In javascript objects also contain another object.
// nested object
const person = {
name: 'John',
age: 30,
job: {
position: 'engineer',
sallary: 5000
}
}
// accessing property of student object
console.log(person.job); //Output : {science: 70, math: 75}
// accessing property of marks object
console.log(person.job.position); //Output : 70
// Output :
Object { position: "engineer", sallary: 5000 }
"Engineer"
