reduce array of objects to one object code example

Example 1: javascript Convert an array of objects to a single object

const toObject = (arr, key) => arr.reduce((a, b) => ({ ...a, [b[key]]: b }), {});

// Example
toObject(
    [
        { id: '1', name: 'June', gender: 'Female' },
        { id: '2', name: 'Alex', gender: 'Male' },
        { id: '3', name: 'Harry', gender: 'Male' },
    ],
    'id'
);
/* 
{
    '1': { id: '1', name: 'June', gender: 'Female' },
    '2': { id: '2', name: 'Alex', gender: 'Male' },
    '3': { id: '3', name: 'Harry', gender: 'Male' },
}
*/

Example 2: javascript reduce array of objects

var objs = [
  {name: "Peter", age: 35},
  {name: "John", age: 27},
  {name: "Jake", age: 28}
];

objs.reduce(function(accumulator, currentValue) {
  return accumulator + currentValue.age;
}, 0); // 35 + 27 + 28 = 90