by Sai gowtham

How to read a JSON file in Deno

In this tutorial, we are going to learn about how to read a JSON file in deno using fs module.

The fs module offers us two different methods to read a JSON file which is readJsonSync() and readJson().

Using the readJsonSync() method

The readJsonSync() method reads the data from a JSON file in a synchronous manner then parses it into an object.

app.js
import { readJsonSync } from "https://deno.land/std/fs/mod.ts";

const users = readJsonSync("./users.json");

console.log(users);

To run the above code, we need to allow deno to read the ./users.json file by using --allow-read flag.

deno run  --allow-read=./users.json --unstable  app.js

Output:

{ user1: "Gowtham", user2: "Leo", user3: "John" }

Note: All the methods inside an fs module are currently unstable, so that we have used the --unstable flag to enable it during the runtime.

Using the readJson() method

The readJson() method works similar like readJsonSync() method, but it reads the JSON file in a asynchronous manner.

app.js
import { readJson } from "https://deno.land/std/fs/mod.ts";

const users = await readJson("./users.json");

console.log(users);

you can also, checkout writting an object to a JSON file in Deno

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