What is an API Call?
What is an API?
An Application Program Interface (API) acts as a source of communication between software programs. With the help of an API, a developer doesn't have to write the code from scratch. They can simply use an existing API that will save time and resources. Using an API also helps with software integration, which in turn improves the user experience. After developing an API, we make an API call to request resources from the server and perform other operations.
What is an API call?
An API call is a procedure by which information is exchanged. The client sends a request to an API. The API sends the request to the server and gets the response back to the client via that same API.
HTTP methods to make an API call
To communicate with our API, we use the following requests methods:
GET: This requests data from a resource. This method only retrieves data.POST: This method creates new resources on the server. It accepts a request body. The API then takes that request body to the server to perform the create operation in the database.PUT: This method modifies a record by replacing the existing one with the updated one.HEAD: This requests data from a resource without retrieving it. We usually use this method beforeGET.DELETE: This deletes a record from the database.PATCH: This partially updates a resource.CONNECT: This creates a connection with the resource.TRACE: This carries out a message loop-back test.OPTIONS: This method tells us the communication options available for that resource.
How to make an API call
We use the GET method to call an API in Node.js.
Step 1: Install Node.js
Install Node.js from here.
Step 2: Create a directory and open it in a code editor
We then create a directory on our computer and open it in a code editor like VIM, sublime text, VS code, and so on.
Step 3: Set up a Node.js project
This command is going to initialize the Node.js project in the directory. The -y flag will use all the default values.
npm init -yStep 4: Install Axios
Axios is an npm package that lets us call an API in our Node.js project. After this, we create an index.js file.
npm install axiosStep 5: Use a GET request to call an API
Here's how we make the GET request:
// Importing libraries hereconst fetch = require("node-fetch");// Define endpoint URL here// const endpointUrl = "https://api.sandbox.transferwise.tech/v1/rates";const endpointUrl = 'https://jsonplaceholder.typicode.com/posts';// Define Header Parameters hereconst headerParameters = {// authorization: API_KEY,"Content-Type": "application/json",};// Setting API call optionsconst options = {method: "get",headers: headerParameters,};// Function to make API callasync function fetchSomethingJSON() {try {const response = await fetch(endpointUrl, options);// Printing responseprintResponse(response);} catch (error) {// Printing error messageprintError(response);}}// Calling function to make API callfetchSomethingJSON();
const axios = require('axios');(async () => {const makeGETRequest = async url => {try {const response = await axios.get(url);return response.data;} catch (error) {console.log(error);}};const response = await makeGETRequest('https://jsonplaceholder.typicode.com/posts');console.log(response);})();
Code explanation
Line 1: We import Axios.
Lines 3–4: We create an
immediately invoke function expression (IIFE) A JavaScript function that runs as soon as it is defined. awaita function that we use later in the code. To do that, we wrap it in an async function. Moreover, when our file executes, this function will automatically be executed. We won't have to call it specifically. We then make amakeGETRequestfunction that is asynchronous.Lines 5–11: We make an HTTP
GETrequest to an external API that will return a list of posts. To make theGETrequest, we useaxios.get(url). We put our request in atryandcatchblock to deal with errors. We used theawaitkeyword to ensure the data was received.Lines 13–16: We call our
makeGETRequestfunction by putting the URL of the external API.
Step 6: Run your code
Run your code by using the following command:
node index.jsWe can use the other HTTP methods in the same way. The only thing we need to change would be replacing get with the method's name. For example, if we want to send a POST request, we would use axios.post(url) instead of axios.get(url).
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