Javascript get request with headers

Request: Request() constructor

The Request() constructor creates a new Request object.

Syntax

new Request(input) new Request(input, options) 

Parameters

Defines the resource that you wish to fetch. This can either be:

• A string containing the URL of the resource you want to fetch. The URL may be relative to the base URL, which is the document’s baseURI in a window context, or WorkerGlobalScope.location in a worker context.
• A Request object, effectively creating a copy. Note the following behavioral updates to retain security while making the constructor less likely to throw exceptions:
  • If this object exists on another origin to the constructor call, the Request.referrer is stripped out.
  • If this object has a Request.mode of navigate , the mode value is converted to same-origin .

  An object containing any custom settings that you want to apply to the request. The possible options are:

  The request method, e.g., GET , POST . The default is GET .

  Any headers you want to add to your request, contained within a Headers object or an object literal with String values.

  Any body that you want to add to your request: this can be a Blob , an ArrayBuffer , a TypedArray , a DataView , a FormData , a URLSearchParams , a string, or a ReadableStream object. Note that a request using the GET or HEAD method cannot have a body.

  The mode you want to use for the request, e.g., cors , no-cors , same-origin , or navigate . The default is cors .

  The request credentials you want to use for the request: omit , same-origin , or include . The default is same-origin .

  The cache mode you want to use for the request.

  The redirect mode to use: follow , error , or manual . The default is follow .

  A string specifying no-referrer , client , or a URL. The default is about:client .

  A string that changes how the referrer header is populated during certain actions (e.g., fetching subresources, prefetching, performing navigations).

  Contains the subresource integrity value of the request (e.g., sha256-BpfBw7ivV8q2jLiT13fxDYAe2tJllusRSZ273h2nFSE= ).

  A boolean that indicates whether to make a persistent connection for multiple requests/responses.

  An AbortSignal object which can be used to communicate with/abort a request.

  Specifies the priority of the fetch request relative to other requests of the same type. Must be one of the following strings:

  • high : A high priority fetch request relative to other requests of the same type.
  • low : A low priority fetch request relative to other requests of the same type.
  • auto : Automatically determine the priority of the fetch request relative to other requests of the same type (default).

  If you construct a new Request from an existing Request , any options you set in an options argument for the new request replace any corresponding options set in the original Request . For example:

  const oldRequest = new Request( "https://github.com/mdn/content/issues/12959",  headers:  From: "webmaster@example.org" > >, ); oldRequest.headers.get("From"); // "webmaster@example.org" const newRequest = new Request(oldRequest,  headers:  From: "developer@example.org" >, >); newRequest.headers.get("From"); // "developer@example.org" 

  Errors

  Type	Description
  TypeError	Since Firefox 43, Request() will throw a TypeError if the URL has credentials, such as http://user:password@example.com.

  Examples

  In our Fetch Request example (see Fetch Request live) we create a new Request object using the constructor, then fetch it using a fetch() call. Since we are fetching an image, we run Response.blob on the response to give it the proper MIME type so it will be handled properly, then create an Object URL of it and display it in an element.

  const myImage = document.querySelector("img"); const myRequest = new Request("flowers.jpg"); fetch(myRequest) .then((response) => response.blob()) .then((response) =>  const objectURL = URL.createObjectURL(response); myImage.src = objectURL; >); 

  In our Fetch Request with init example (see Fetch Request init live) we do the same thing except that we pass in an options object when we invoke fetch() :

  const myImage = document.querySelector("img"); const myHeaders = new Headers(); myHeaders.append("Content-Type", "image/jpeg"); const myOptions =  method: "GET", headers: myHeaders, mode: "cors", cache: "default", >; const myRequest = new Request("flowers.jpg", myOptions); fetch(myRequest).then((response) =>  // . >); 

  Note that you could also pass myOptions into the fetch call to get the same effect, e.g.:

  fetch(myRequest, myOptions).then((response) =>  // . >); 

  You can also use an object literal as headers in myOptions .

  const myOptions =  method: "GET", headers:  "Content-Type": "image/jpeg", >, mode: "cors", cache: "default", >; const myRequest = new Request("flowers.jpg", myOptions); 

  You may also pass a Request object to the Request() constructor to create a copy of the Request (This is similar to calling the clone() method.)

  const copy = new Request(myRequest); 

  Note: This last usage is probably only useful in ServiceWorkers.

  Specifications

  Browser compatibility

  BCD tables only load in the browser

  See also

  Found a content problem with this page?

  This page was last modified on Jul 7, 2023 by MDN contributors.

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  Источник

  Как отправить или получить HTTP заголовки на JavaScript

  

  05.12.18 ИТ / JavaScript 13833

  Обычно для работы с заголовками используется серверный язык, однако можно попробовать использовать и JavaScript (JS).

  

  Как отправить HTTP заголовки запроса

  Отправить заголовки на JavaScript можно при помощи Ajax-запросов. На чистом языке без применения библиотек это может выглядеть так:

  var request = new XMLHttpRequest(); request.open('GET', document.location, false); request.setRequestHeader('Accept', 'text/plain'); request.setRequestHeader('Content-Type', 'text/plain'); request.setRequestHeader('Content-Language', 'en-US'); request.send(null); request.getAllResponseHeaders().toLowerCase();

  Как получить HTTP заголовки ответа

  Получить заголовки на JavaScript задача посложней, так как это язык работает на стороне клиента. Но можно отправить запрос на сервер средствами Ajax и получить примерно похожие заголовки при помощи функции getAllResponseHeaders. Примерный код:

  var request = new XMLHttpRequest(); request.open('GET', document.location, false); request.send(null); request.getAllResponseHeaders().toLowerCase();

  Таким образом, отправить или получить заголовки можно и при помощи языка JavaScript, а не только при помощи серверных языков, наподобие PHP.

  Источник

  Читайте также:  Python запуск bash скрипта