Dot vs Bracket object notation in Javascript

Published June 15, 2020

Consider this object,

const Person = {
  name: "John",
  age: 23,
  email: "john@example.com",
};

We can access this object's properties using the dot notation and bracket notation.

Dot Notation - .

Let's access the name property on the Person object.

const Person = {
  name: "John",
  age: 23,
  email: "john@example.com",
};

// using dot notation
const personName = Person.name; // Result: John
  • Properties can be accessed using the . after the object's name followed by the property name you need to access.
  • It most common way of retrieving property from an object.

Bracket Notation - []

We can use our old object Person.

const Person = {
  name: "John",
  age: 23,
  email: "john@example.com",
};

// using bracket notation
const personName = Person["name"]; // Result: John
  • Properties can be accessed using [] after the object's name followed by the property name inside the bracket.

Why do we need bracket notation if we have dot notation?

  • Bracket notation helps in getting computed value.

Consider this object,

// defining new variable with value age
const propertyName = "age";

const Person = {
  name: "John",
  age: 23,
  email: "john@example.com",
};

// access object property by passing variable value
Person[propertyName]; // Result: 23

Here the Person Object is given variable propertyName inside the bracket. JavaScript checks the value of the variable and puts that value into the bracket and then returns the property value from the object.

Bracket notation is useful when working with dynamic data.

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