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What is the best way to reduce and merge a collection of objects – JavaScript?
The best way to reduce and merge a collection of objects, use the concept of Object.values() along with reduce().
Following is the object −
var details = [
{ studentId: 10, marks: 75, studentName: "John" },
{ studentId: 10, marks: 75, studentName: "John" },
{ studentId: 11, marks: 98, studentName: "Bob" }
];Example
Following is the code to reduce and merge −
var details = [
{ studentId: 10, marks: 75, studentName: "John" },
{ studentId: 10, marks: 75, studentName: "John" },
{ studentId: 11, marks: 98, studentName: "Bob" }
];
output = Object.values(details.reduce((value, object) => {
if (value[object.studentId]) {
['marks'].forEach(key => value[object.studentId][key] = value[object.studentId][key] + object[key]);
} else {
value[object.studentId] = { ...object };
}
return value;
}, {}));
console.log(output);To run the above program, use the following command −
node fileName.js.
Here, my file name is demo237.js.
Output
The output is as follows −
PS C:\Users\Amit\javascript-code> node demo237.js
[
{ studentId: 10, marks: 150, studentName: 'John' },
{ studentId: 11, marks: 98, studentName: 'Bob' }
]
Updated on: 03-Oct-2020
573 Views
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