How to Compare Two Objects using Lodash?

To compare two objects using lodash, we employ Lodash functions such as _.isEqual(), _.isMatch(), and _.isEqualWith(). These methods enable us to do a comparison between two objects and determine if they are equivalent or not.

Below are the approaches to do a comparison between two objects using Lodash:

Run the below command to install Lodash JavaScript Library:

npm install lodash

Using Lodash _.isEqual() Method

In this approach, we use the _.isEqual() from Lodash to do a comparison between two values to determine if they are equivalent. This method supports comparing arrays, array buffers, boolean, date objects, maps, numbers, objects, regex, sets, strings, symbols, and typed arrays. 

Syntax:

 _.isEqual( value1, value2);

Example: The below example shows how to do a comparison between 2 objects with lodash using _the .isEqual() Method.

// Defining Lodash variable 
const _ = require('lodash');

// First object
const obj1 = { a: 1, b: { c: 2, d: [3, 4] } };

// Second object
const obj2 = { a: 1, b: { c: 2, d: [3, 4] } };

// Checking for Equal Value 
const isEqual = _.isEqual(obj1, obj2);
console.log(isEqual);

Output:

true

Using Lodash _.isMatch() Method

In this approach, we are using the Lodash _.isMatch() method to perform a partial comparison between other object and sources to determine if the object contains equivalent property values.

Syntax:

_.isMatch(object, source);

Example: The below example shows how to do a comparison between 2 objects with lodash using the _.isMatch() method.

// Defining Lodash variable 
const _ = require('lodash');

// First object
const obj = { a: 1, b: { c: 2, d: [3, 4] } };

// Second object
const source = { b: { c: 2 } };

// Doing a deep comparison
const isMatch = _.isMatch(obj, source);
console.log(isMatch);

Output:

true

Using _.isEqualWith() Method

In this approach, we are using the _.isEqualWith() method to do a deep comparison between two values to determine if they are equivalent. Also, it accepts a customizer which is called to compare values. Moreover, if the customizer used here returns undefined then the comparisons are dealt with by the method instead. 

Syntax:

_.isEqualWith(value, other, [customizer]);

Example: The below example shows how to do a deep comparison between 2 objects with lodash using the isEqualWith() method.

// Import the lodash library
const _ = require('lodash');

// Define two objects to be compared
const obj1 = { a: 1, b: { c: 2, d: [3, 4] } };
const obj2 = { a: 1, b: { c: 2, d: [3, 4] } };
const customizer = (value1, value2) => {
    
    // Check if both values are arrays
    if (_.isArray(value1) && _.isArray(value2)) {
        
        // If both values are arrays, compare them after sorting
        return _.isEqual(_.sortBy(value1), _.sortBy(value2));
    }
};
const isEqualWith = _.isEqualWith(obj1, obj2, customizer);
console.log(isEqualWith);

Output:

true

Using Lodash _.differenceWith() Method

In this approach, we use the _.differenceWith() method from Lodash to find the difference between two arrays of objects using a custom comparator function. This method returns an array of elements that are not present in the other array, helping to identify differences between the two objects.

Syntax:

_.differenceWith(array, [values], [comparator]);

Example: The below example shows how to compare two arrays of objects with Lodash using the _.differenceWith() method.

// Import the lodash library
const _ = require('lodash');

// Define two arrays of objects
const array1 = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
const array2 = [{ 'x': 1, 'y': 2 }, { 'x': 1, 'y': 2 }];

// Use differenceWith to find the difference
const difference = _.differenceWith(array1, array2, _.isEqual);
console.log(difference);

Output:

[ { x: 2, y: 1 } ]

Using Lodash _.isMatchWith() Method

In this approach, we use the _.isMatchWith() method to perform a partial comparison between two objects with custom comparison logic. This method allows you to customize how the comparison is done for specific properties.

Syntax:

_.isMatchWith(object, source, customizer);

Example: The below example shows how to compare two objects with Lodash using the _.isMatchWith() method.

// Import the lodash library
const _ = require('lodash');

// Define two objects to be compared
const obj1 = { a: 1, b: { c: 2, d: [3, 4] } };
const obj2 = { a: 1, b: { c: 2, d: [3, 5] } };

// Customizer function for comparison
const customizer = (objValue, srcValue) => {
    if (_.isArray(objValue) && _.isArray(srcValue)) {
        return _.difference(objValue, srcValue).length === 0;
    }
};

// Use isMatchWith for partial comparison
const isMatchWith = _.isMatchWith(obj1, obj2, customizer);
console.log(isMatchWith);

Output:

false