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Lodash _.size


The _.size method in Lodash is a utility function that returns the number of elements in a collection. This method can be used with arrays, objects, and strings in JavaScript.




  • collection (Array|Object|string): The collection to inspect.

Return Value:

  • (number): Returns the size of the collection.


  1. Using _.size with an array:
const arr = [1, 2, 3, 4, 5];
const size = _.size(arr);
console.log(size); // Output: 5
  1. Using _.size with an object:
const obj = {
  name: 'John',
  age: 30,
  city: 'New York'
const size = _.size(obj);
console.log(size); // Output: 3
  1. Using _.size with a string:
const str = 'hello world';
const size = _.size(str);
console.log(size); // Output: 11


  • For arrays and strings, _.size returns the number of elements in the collection.
  • For objects, _.size returns the number of enumerable properties in the object.
  • If the collection is null or undefined, _.size returns 0.
  • If the collection is not an array, object, or string, _.size returns undefined.
  • This method is part of the Lodash library, which is a popular utility library for JavaScript. To use _.size, you must first include the Lodash library in your project.

In conclusion, the _.size method in Lodash is a simple and useful utility function that returns the number of elements in a collection. It can be used with arrays, objects, and strings in JavaScript, and it returns 0 for null or undefined collections. By using this method, developers can easily get the size of a collection without having to write complex code.