JavaScript - convert array of objects to hash map (indexed by property value)

In this article, we would like to show you how to convert an array of objects to a hash map in JavaScript.

Quick solution (ES6+):

// ONLINE-RUNNER:browser;

const array = [{ key: 1, value: 'a' }, { key: 2, value: 'b' }];

const result = array.reduce((map, object) => ((map[object.key] = object.value), map), {});

console.log(JSON.stringify(result)); // { '1': 'a', '2': 'b' }

Practical example

In this example, we use reduce() method to convert an array of objects into a hash map containing key/value pairs created with property values.

// ONLINE-RUNNER:browser;

var array = [
    { key: 1, value: 'a' },
    { key: 2, value: 'b' }
];

var result = array.reduce(function(map, object) {
    map[object.key] = object.value;
    return map;
}, {});

console.log(JSON.stringify(result)); // { '1': 'a', '2': 'b' }

References

1. Array.prototype.reduce() - JavaScript | MDN