Get command in html

HTTP Request Methods

The Hypertext Transfer Protocol (HTTP) is designed to enable communications between clients and servers.

HTTP works as a request-response protocol between a client and server.

Example: A client (browser) sends an HTTP request to the server; then the server returns a response to the client. The response contains status information about the request and may also contain the requested content.

HTTP Methods

The two most common HTTP methods are: GET and POST.

The GET Method

GET is used to request data from a specified resource.

Note that the query string (name/value pairs) is sent in the URL of a GET request:

Some notes on GET requests:

• GET requests can be cached
• GET requests remain in the browser history
• GET requests can be bookmarked
• GET requests should never be used when dealing with sensitive data
• GET requests have length restrictions
• GET requests are only used to request data (not modify)

The POST Method

POST is used to send data to a server to create/update a resource.

The data sent to the server with POST is stored in the request body of the HTTP request:

POST /test/demo_form.php HTTP/1.1
Host: w3schools.com

Some notes on POST requests:

• POST requests are never cached
• POST requests do not remain in the browser history
• POST requests cannot be bookmarked
• POST requests have no restrictions on data length

Compare GET vs. POST

The following table compares the two HTTP methods: GET and POST.

GET	POST
BACK button/Reload	Harmless	Data will be re-submitted (the browser should alert the user that the data are about to be re-submitted)
Bookmarked	Can be bookmarked	Cannot be bookmarked
Cached	Can be cached	Not cached
Encoding type	application/x-www-form-urlencoded	application/x-www-form-urlencoded or multipart/form-data. Use multipart encoding for binary data
History	Parameters remain in browser history	Parameters are not saved in browser history
Restrictions on data length	Yes, when sending data, the GET method adds the data to the URL; and the length of a URL is limited (maximum URL length is 2048 characters)	No restrictions
Restrictions on data type	Only ASCII characters allowed	No restrictions. Binary data is also allowed
Security	GET is less secure compared to POST because data sent is part of the URL

The PUT Method

PUT is used to send data to a server to create/update a resource.

The difference between POST and PUT is that PUT requests are idempotent. That is, calling the same PUT request multiple times will always produce the same result. In contrast, calling a POST request repeatedly have side effects of creating the same resource multiple times.

The HEAD Method

HEAD is almost identical to GET, but without the response body.

In other words, if GET /users returns a list of users, then HEAD /users will make the same request but will not return the list of users.

HEAD requests are useful for checking what a GET request will return before actually making a GET request — like before downloading a large file or response body.

The DELETE Method

The DELETE method deletes the specified resource.

The PATCH Method

The PATCH method is used to apply partial modifications to a resource.

The OPTIONS Method

The OPTIONS method describes the communication options for the target resource.

The CONNECT Method

The CONNECT method is used to start a two-way communications (a tunnel) with the requested resource.

The TRACE Method

The TRACE method is used to perform a message loop-back test that tests the path for the target resource (useful for debugging purposes).

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HTTP-запрос методом GET.

Одним из способов, как можно отправить запрос по протоколу HTTP к серверу, является запрос методом GET. Этот метод является самым распространенным и запросы к серверу чаще всего происходят с его использованием.

Самый простой способ, как можно создать запрос методом GET- это набрать URL-адрес в адресную строку браузера.

Если у вас есть желание погрузиться в тему серверного программирования глубже, все мои уроки здесь.

Браузер передаст серверу примерно следующую информацию:

GET / HTTP/1.1 Host: site.ru User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:18.0) Gecko/20100101 Firefox/18.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: ru-RU,ru;q=0.8,en-US;q=0.5,en;q=0.3 Accept-Encoding: gzip, deflate Cookie: wp-settings Connection: keep-alive

Запрос состоит из двух частей:

1. строка запроса (Request Line)

2. заголовки (Message Headers)

Обратите внимание, что GET запрос не имеет тела сообщения. Но, это не означает, что с его помощью мы не можем передать серверу никакую информацию. Это можно делать с помощью специальных GET параметров.

Чтобы добавить GET параметры к запросу, нужно в конце URL-адреса поставить знак «?» и после него начинать задавать их по следующему правилу:

имя_параметра1=значение_параметра1& имя_параметра2=значение_параметра2&… 
Разделителем между параметрами служит знак «&».

К примеру, если мы хотим передать серверу два значения, имя пользователя и его возраст, то это можно сделать следующей строкой:

http://site.ru/page.php?name=dima&age=27

Когда выполнен данный запрос, данные попадают в так называемую переменную окружения QUERY_STRING, из которой их можно получить на сервере с помощью серверного языка веб-программирования.

Вот пример, как это можно сделать на языке PHP.

"; echo "Ваш возраст: " . $_GET["age"] . "
"; ?>

Конструкция $_GET[«имя_параметра»] позволяет выводить значение переданного параметра.

В результате выполнения этого кода в браузере выведется:

Ваше имя: dima Ваш возраст: 27

Кстати, переходя по какой-либо ссылке, которая оформлена в HTML вот так:

мы тоже выполняем запрос к серверу методом GET.

Все мои уроки по серверному программированию здесь.

Чтобы оставить сообщение, зарегистрируйтесь/войдите на сайт через:

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JavaScript Get Request – How to Make an HTTP Request in JS

Joel Olawanle

When building applications, you will have to interact between the backend and frontend to get, store, and manipulate data.

This interaction between your frontend application and the backend server is possible through HTTP requests.

There are five popular HTTP methods you can use to make requests and interact with your servers. One HTTP method is the GET method, which can retrieve data from your server.

This article will teach you how to request data from your servers by making a GET request. You will learn the popular methods that exist currently and some other alternative methods.

For this guide, we’ll retrieve posts from the free JSON Placeholder posts API.

There are two popular methods you can easily use to make HTTP requests in JavaScript. These are the Fetch API and Axios.

How to Make a GET Request with the Fetch API

The Fetch API is a built-in JavaScript method for retrieving resources and interacting with your backend server or an API endpoint. Fetch API is built-in and does not require installation into your project.

Fetch API accepts one mandatory argument: the API endpoint/URL. This method also accepts an option argument, which is an optional object when making a GET request because it is the default request.

Let’s create a GET request to get a post from the JSON Placeholder posts API.

fetch("https://jsonplaceholder.typicode.com/posts/1") .then((response) => response.json()) .then((json) => console.log(json)); 

This will return a single post which you can now store in a variable and use within your project.

Note: For other methods, such as POST and DELETE, you need to attach the method to the options array.

How to Make a GET Request with Axios

Axios is an HTTP client library. This library is based on promises that simplify sending asynchronous HTTP requests to REST endpoints. We will send a GET request to the JSONPlaceholder Posts API endpoint.

Axios, unlike the Fetch API, is not built-in. This means you need to install Axios into your JavaScript project.

To install a dependency into your JavaScript project, you will first initialize a new npm project by running the following command in your terminal:

And now you can install Axios to your project by running the following command:

Once Axios is successfully installed, you can create your GET request. This is quite similar to the Fetch API request. You will pass the API endpoint/URL to the get() method, which will return a promise. You can then handle the promise with the .then() and .catch() methods.

axios.get("https://jsonplaceholder.typicode.com/posts/1") .then((response) => console.log(response.data)) .catch((error) => console.log(error)); 

Note: The major difference is that, for Fetch API, you first convert the data to JSON, while Axios returns your data directly as JSON data.

At this point, you have learned how to make a GET HTTP request with Fetch API and Axios. But there are some other methods that still exist. Some of these methods are XMLHttpRequest and jQuery.

How to Make a GET Request with XMLHttpRequest

You can use the XMLHttpRequest object to interact with servers. This method can request data from a web server’s API endpoint/URL without doing a full page refresh.

Note: All modern browsers have a built-in XMLHttpRequest object to request data from a server.

Let’s perform the same request with the XMLHttpRequest by creating a new XMLHttpRequest object. You will then open a connection by specifying the request type and endpoint (the URL of the server), then you’ll send the request, and finally listen to the server’s response.

const xhr = new XMLHttpRequest(); xhr.open("GET", "https://jsonplaceholder.typicode.com/posts/1"); xhr.send(); xhr.responseType = "json"; xhr.onload = () => < if (xhr.readyState == 4 && xhr.status == 200) < console.log(xhr.response); >else < console.log(`Error: $`); > >; 

In the above code, a new XMLHttpRequest object is created and stored in a variable called xhr . You can now access all its objects using the variable, such as the .open() method, when you specify the request type (GET) and the endpoint/URL where you want to request data.

Another method you will use is .send() , which sends the request to the server. You can also specify the format in which the data will be returned using the responseType method. At this point, the GET request is sent, and all you have to do is listen to its response using the onload event listener.

If the client’s state is done (4), and the status code is successful (200), then the data will be logged to the console. Otherwise, an error message showing the error status will appear.

How to Make a GET Request with jQuery

Making HTTP requests in jQuery is relatively straightforward and similar to the Fetch API and Axios. To make a GET request, you will first install jQuery or make use of its CDN in your project:

With jQuery, you can access the GET method $.get() , which takes in two parameters, the API endpoint/URL and a callback function that runs when the request is successful.

$.get("https://jsonplaceholder.typicode.com/posts/1", (data, status) => < console.log(data); >); 

Note: In the callback function, you have access to the request’s data and the request’s status.

You can also use the jQuery AJAX Method, which is quite different and can be used to make asynchronous requests:

Wrapping Up

In this article, you have learned how to make the HTTP GET request in JavaScript. You might now begin to think — which method should I use?

If it’s a new project, you can choose between the Fetch API and Axios. Also, if you want to consume basic APIs for a small project, there is no need to use Axios, which demands installing a library.

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