How to Replace Objects in Array using Lodash?

Replacing objects in an array using Lodash typically involves identifying the specific object(s) you want to replace and then performing the replacement operation. Lodash provides a range of methods to facilitate such operations, although the actual replacement might involve combining Lodash functions with native JavaScript methods.

Below are different possible approaches to replacing objects in an array using Lodash:

Using _.findIndex ( ) and Direct Replacement

• Use _.findIndex(array, condition) to find the index of the object that matches a given condition in the array.
• Use the found index to directly replace the object in the array with a new object, updating the array in place.

Example: Below is an example code of the above approach where we are given an array of objects representing students, and you want to update the grade of a specific student. Let us suppose, we want to update Smrita's grade to A.

// Import Lodash using require
const _ = require('lodash');

// Initial array of students
const students = [
    { id: 1, name: "Ayush", grade: "B" },
    { id: 2, name: "Smrita", grade: "C" },
    { id: 3, name: "Antima", grade: "A" },
];

// Find the index of the object to replace (Smrita, in this case)
const index = _.findIndex(students, { id: 2 });

if (index !== -1) {
    // Replace the object at the found index with the updated object
    students[index] = { ...students[index], grade: "A" };
}

// Output
console.log(students);

Output:

[
  { id: 1, name: "Ayush", grade: "B" },
  { id: 2, name: "Smrita", grade: "A" },
  { id: 3, name: "Antima", grade: "A" },
]

Using _.map( )to Create a New Array

• Use _.map(array, iteratee) to iterate over the array, where iteratee is a function that checks each object and replaces the specific object if it matches a condition.
• This approach creates a new array with the updated objects instead of modifying the original array, preserving immutability.

Example: This code updates the grade of the student with id 2 to "A" and creates a new array with the modified student object.

// Import Lodash using require
const _ = require('lodash');

// Initial array of students
const students = [
    { id: 1, name: "Ayush", grade: "B" },
    { id: 2, name: "Smrita", grade: "C" },
    { id: 3, name: "Antima", grade: "A" },
];

// Create a new array with the updated object using _.map
const updatedStudents = _.map(students, (student) =>
    student.id === 2 ? { ...student, grade: "A" } : student
);

// Output
console.log(updatedStudents);

Output:

[
  { id: 1, name: "Ayush", grade: "B" },
  { id: 2, name: "Smrita", grade: "A" },
  { id: 3, name: "Antima", grade: "A" },
]

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Article Tags :

• JavaScript
• Web Technologies
• JavaScript-Lodash