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Lodash _.merge() Method

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Lodash _.merge() method is used to merge two or more objects starting with the left-most to the right-most to create a parent mapping object. When two keys are the same, the generated object will have a value for the rightmost key.

If more than one object is the same, the newly generated object will have only one key(most right side) and value corresponding to those objects.

Note: The _.merge() method mutates the object.

Syntax:

_.merge(object, [sources])

Parameters:

  • object parameter holds the destination object.
  • sources parameter holds the source object. It is an optional parameter.

Return Value:

This method returns the merged object.

Example 1: In this example, when two keys are the same then only the right-most key will be added to a new array, and if more than two objects are the same then it will add only one.

Javascript




// Requiring the lodash library 
const _ = require("lodash");
 
// Using the _.merge() method
console.log(
    _.merge({ cpp: "12" }, { java: "23" },
        { python: "35" })
);
 
// When two keys are the same
console.log(
    _.merge({ cpp: "12" }, { cpp: "23" },
        { java: "23" }, { python: "35" })
);
 
// When more than one object is the same
console.log(
    _.merge({ cpp: "12" }, { cpp: "12" },
        { java: "23" }, { python: "35" })
);


Output:

{ cpp: '12', java: '23', python: '35' }
{ cpp: '23', java: '23', python: '35' }
{ cpp: '12', java: '23', python: '35' }

Example 2: In this example, when we are merging two different objects then it will merge recursively(one right-most element from ‘other’ and one right-most element from ‘object’).

Javascript




// Requiring the lodash library 
const _ = require("lodash");
 
// The destination object
let object = {
    'amit': [{ 'susanta': 20 }, { 'durgam': 40 }]
};
 
// The source object
let other = {
    'amit': [{ 'chinmoy': 30 }, { 'kripamoy': 50 }]
};
 
// Using the _.merge() method
console.log(_.merge(object, other));


Output:

{
  amit: [ { susanta: 20, chinmoy: 30 }, { durgam: 40, kripamoy: 50 } ]
}


Last Updated : 18 Oct, 2023
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