Syntax error Most efficient method to groupby on an array of objects in Javascript

Most efficient method to groupby on an array of objects in Javascript

The most efficient method to group by a key on an array of objects in js is to use the reduce function.

The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in a single output value.

Example

const people = [
   { name: 'Lee', age: 21 },
   { name: 'Ajay', age: 20 },
   { name: 'Jane', age: 20 }
];
function groupBy(objectArray, property) {
   return objectArray.reduce((acc, obj) => {
      const key = obj[property];
      if (!acc[key]) {
         acc[key] = [];
      }
      // Add object to list for given key's value
      acc[key].push(obj);
      return acc;
   }, {});
}
const groupedPeople = groupBy(people, 'age');
console.log(groupedPeople);

Output

This will give the output −

{ 20: [ { name: 'Ajay', age: 20 }, { name: 'Jane', age: 20 } ],
21: [ { name: 'Lee', age: 21 } ] }
Updated on: 2019-11-27T10:48:44+05:30

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