How to get object length in JavaScript

Use the Object keys method to get object length in JavaScript. You can also find the length of the values inside the object.

var size = Object.keys(myObj).length;

Strings: You can use the length property of a string to get its length.

const myString = "Hello, World!";
const stringLength = myString.length;
console.log(stringLength); // Outputs: 13

Arrays: Arrays have a length property as well, which gives you the number of elements in the array.

const myArray = [1, 2, 3, 4, 5];
const arrayLength = myArray.length;
console.log(arrayLength); // Outputs: 5

Objects: In JavaScript, objects do not have a built-in length property like strings and arrays. To get the number of properties (keys) in an object, you can use a for...in loop or Object.keys() method.

Using a for...in loop:

const myObject = {
  name: "John",
  age: 30,
  city: "New York"
};

let objectLength = 0;
for (const key in myObject) {
  if (myObject.hasOwnProperty(key)) {
    objectLength++;
  }
}

console.log(objectLength); // Outputs: 3

Using Object.keys():

const myObject = {
  name: "John",
  age: 30,
  city: "New York"
};

const objectKeys = Object.keys(myObject);
const objectLength = objectKeys.length;
console.log(objectLength); // Outputs: 3

Map and Set: You can get the size (number of key-value pairs) of a Map or the number of elements in a Set using their size property.

const myMap = new Map();
myMap.set("key1", "value1");
myMap.set("key2", "value2");

const mapSize = myMap.size;
console.log(mapSize); // Outputs: 2

const mySet = new Set([1, 2, 3, 4, 5]);
const setSize = mySet.size;
console.log(setSize); // Outputs: 5

These are the common ways to get the length or size of various objects in JavaScript. Depending on the type of object you are working with, you can choose the appropriate method to determine its length or size.