How to Make HTTP Request in Deno: Simple Guide

In Deno, you make HTTP requests using the built-in fetch function, which works like in browsers. You call fetch(url) to send a request and then use await to get the response and read its data.

Syntax

The basic syntax to make an HTTP request in Deno uses the fetch function:

• fetch(url, options): Sends a request to the given URL.
• url: The address you want to request.
• options: Optional object to specify method, headers, body, etc.
• await: Used to wait for the response asynchronously.
• response.json() or response.text(): Methods to read the response data.

typescript

const response = await fetch('https://example.com/api', {
  method: 'POST', // or 'GET', 'PUT', etc.
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ key: 'value' }) // only for methods like POST
});
const data = await response.json();

Example

This example shows how to make a GET request to fetch JSON data from a public API and print it to the console.

typescript

const response = await fetch('https://jsonplaceholder.typicode.com/todos/1');
if (!response.ok) {
  console.error('HTTP error:', response.status);
} else {
  const todo = await response.json();
  console.log('Todo item:', todo);
}

Output

{"userId":1,"id":1,"title":"delectus aut autem","completed":false}

Common Pitfalls

Common mistakes when making HTTP requests in Deno include:

• Not using await with fetch, which causes unresolved promises.
• Ignoring the response.ok property to check if the request succeeded.
• Forgetting to set the correct Content-Type header when sending JSON data.
• Trying to read the response body multiple times, which is not allowed.

typescript

/* Wrong way: Missing await and no error check */
const response = fetch('https://jsonplaceholder.typicode.com/todos/1');
const data = await response.json(); // Error: response is a Promise, not Response

/* Right way: Use await and check response.ok */
const responseCorrect = await fetch('https://jsonplaceholder.typicode.com/todos/1');
if (responseCorrect.ok) {
  const dataCorrect = await responseCorrect.json();
  console.log(dataCorrect);
} else {
  console.error('Request failed with status', responseCorrect.status);
}

Quick Reference

Here is a quick summary of key points for HTTP requests in Deno:

• Use fetch(url, options) to send requests.
• Always await the fetch call to get the response.
• Check response.ok to confirm success.
• Use response.json() or response.text() to read data.
• Set headers like Content-Type when sending JSON.

Key Takeaways

Use the built-in fetch function with await to make HTTP requests in Deno.

Always check response.ok to handle errors properly.

Set appropriate headers when sending data, especially Content-Type for JSON.

Read the response body only once using methods like response.json() or response.text().

Remember fetch works like in browsers, so no extra libraries are needed.