Creating Object From Entries

We can create objects using Object.create(), using the curly bracket notation {}, with the new operator or ES6 Classes. ES2019 allows us to create objects from entries. Entries refer to a list of key-value pair.

const entries = new Map([
    ["name", "Parwinder"],
    ["title", "Software Architect"],
    ["age", 97]
]);

const obj = Object.fromEntries(entries);

console.log(obj);

The output will be:

{
  age: 97,
  name: "Parwinder",
  title: "Software Architect"
}

You do not necessarily have to use a Map in fromEntries. It works with any iterable like Array, Map or objects implementing iterables.

We can re-write the above example using Arrays.

const entries = [
    ["name", "Parwinder"],
    ["title", "Software Architect"],
    ["age", 97]
];

const obj = Object.fromEntries(entries);

console.log(obj);

It will yield the same output.

🚨 Object.fromEntries is the exact opposite of Object.entries.

Real-life example

Plenty of times we need the URL query params, and we all have a helper method in our code snippets, or we copy something from StackOverflow. JavaScript introduced URLSearchParams to make our lives easy. We can pair it with fromEntries to get a more readable output.

const queryParams = "redirectFrom=login&css=blue&token=747";
const params = new URLSearchParams(queryParams);

const paramObject = Object.fromEntries(params);

console.log(paramObject); // { css: "blue", redirectFrom: "login", token: "747" }
console.log(paramObject.redirectFrom); // "login"
console.log(paramObject.css); // "blue"
console.log(paramObject.token); // "747"