Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, strings, objects, numbers, etc.
The _.mergeWith() method uses a customizer function that is invoked to produce the merged values of the given destination and source properties. When the customizer function returns undefined, the merging is handled by the method instead. It is almost the same as _.merge() method.
Syntax:
_.mergeWith( object, sources, customizer )
Parameters: This method accepts three parameters as mentioned above and described below:
- object: This parameter holds the destination object.
- sources: This parameter holds the source object. It is an optional parameter.
- customizer: This is the function to customize assigned values.
Return Value: This method returns the object.
Example 1:
Javascript
// Requiring the lodash library  const _ = require("lodash");    // The destination object var object = {   'amit': [{ 'susanta': 20 }, { 'durgam': 40 }] };    // The source object var other = {   'amit': [{ 'chinmoy': 30 }, { 'kripamoy': 50 }] };   // Using the _.mergeWith() method console.log(_.mergeWith(object, other)); |
Output:
{ ‘amit’: [{‘chinmoy’: 30, ‘susanta’: 20 }, { ‘durgam’: 40, ‘kripamoy’: 50 }] }
Example 2: Â
Javascript
// Requiring the lodash library  const _ = require("lodash");    // Defining the customizer function function customizer(obj, src) {   if (_.isArray(obj)) {     return obj.concat(src);   } }    // The destination object var object = {   'amit': [{ 'susanta': 20 }, { 'durgam': 40 }] };    // The source object var other = {   'amit': [{ 'chinmoy': 30 }, { 'kripamoy': 50 }] };   // Using the _.mergeWith() method console.log(_.mergeWith(object, other, customizer)); |
Output:
{ ‘amit’: [{‘susanta’: 20 }, { ‘durgam’: 40}, {‘chinmoy’: 30}, {‘kripamoy’: 50 } ]}
