A user agent is a computer program representing a person, for example, a browser in a Web context.
Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.
Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.
A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".
Intercept and modify the contents of a request at various stages of its lifetime. The methods of WebQuest accept an optional filter and a listener.
The listener will be called with listener(details, callback) before sending an HTTP request, once the request headers are available. This may occur after a TCP connection is made to the server, but before any HTTP data is sent.
The callback has to be called with a response object. For HTTP requests, this means that the status line and response headers are available.
It’s all great if we just fetch HTML and parse it with cheerio. Now, we need to scrape a website with JS enabled, because website is doing black magic client side rendering.
We currently recommend to not use the web view tag and to consider alternatives, like iframe, Electron's BrowserView, or an architecture that avoids embedded content altogether. By default, the web view tag is disabled in Electron >= 5.
You need to enable the tag by setting the webviewTag preferences option when constructing your BrowserWindow. Display external web content in an isolated frame and process.
Use the web view tag to embed 'guest' content (such as web pages) in your Electron app. An embedded page within your app controls how the guest content is laid out and rendered.
Unlike an iframe, the web view runs in a separate process than your app. It doesn't have the same permissions as your web page and all interactions between your app and embedded content will be asynchronous.
You can not add keyboard, mouse, and scroll event listeners to web view. All reactions between the embedded frame and web view are asynchronous.
Please note that the web view tag's style uses display:flex; internally to ensure the child iframe element fills the full height and width of its web view container when used with traditional and flex box layouts. Assigning src its own value will reload the current page.
When this attribute is present the guest page in web view will have node integration and can use node APIs like require and process to access low level system resources. Node integration is disabled by default in the guest page.
A Boolean for the experimental option for enabling NodeJS support in sub-frames such as iframes inside the web view. All your preloads will load for every iframe, you can use process.mainframe to determine if you are in the main frame or not.
When this attribute is false the guest page in web view will not have access to the remote module. When this attribute is present the guest page in web view will be able to use browser plugins.
The protocol of script's URL must be either file: or agar:, because it will be loaded by require in guest page under the hood. Note: This option will appear as preloader (not preload) in the preferences specified to the will-attach-webview event.
A String that sets the referrer URL for the guest page. Once the page is loaded, use the setUserAgent method to change the user agent.
When this attribute is present the guest page will have web security disabled. By assigning the same partition, multiple pages can share the same session.
This value can only be modified before the first navigation, since the session of an active renderer process cannot change. Subsequent attempts to modify the value will fail with a DOM exception.
When this attribute is present the guest page will be allowed to open new windows. The full list of supported preference strings can be found in BrowserWindow.
The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file. The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file.
If userGesture is set, it will create the user gesture context in the page. HTML APIs like requestFullScreen, which require user action, can take advantage of this option for automation.
Starts inspecting element at position (x, y) of guest page. Opens the DevTools for the shared worker context present in the guest page.
Starts a request to find all matches for the text in the web page. The result of the request can be obtained by subscribing to found-in-page event.
The following DOM events are available to the web view tag: Fired when the navigation is done, i.e. the spinner of the tab will stop spinning, and the unload event is dispatched.
This event is like did-finish-load, but fired when the load failed or was cancelled, e.g. window.stop() is invoked. Corresponds to the points in time when the spinner of the tab starts spinning.
Corresponds to the points in time when the spinner of the tab stops spinning. ExplicitSet is false when title is synthesized from file URL.
The following example code opens the new URL in system's default browser. It can happen when the window.location object is changed or a user clicks a link in the page.
It is also not emitted during in-page navigation, such as clicking anchor links or updating the window.location.hash. This event is not emitted for in-page navigation, such as clicking anchor links or updating the window.location.hash.
Examples of this occurring are when anchor links are clicked or when the DOM hash change event is triggered. The following example code navigates the web view to about:blank when the guest attempts to close itself.
Rv: gecko version indicates the release version of Gecko (such as 17.0 “). The Chrome (or Chromium/Blink-based engines) user agent string is similar to Firefox’s.
For compatibility, it adds strings like HTML, like Gecko and Safari. The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/
In this example, the user agent string is mobile Safari’s version. When you navigate to a webpage, the response from the server will depend on a number of factors.
The OS being used will be checked (Windows, Linux, Mac or Mobile) along with the browser (Firefox, Chrome, Safari and alike) and possibly the system architecture (x86, x64, etc.) It allows sites to determine specific details, which in turn alters how the page is served to the user.
For instance, menus will be easier to touch and read, and text will be more stripped down and readable. Normally, users are oblivious to the exchange of browser user agent data; there are, however, ways in which users and developers can change the user agent to test for different platforms or simply to mask their browser ID.
Browsers have a fingerprint that can help uniquely identify users with the user agent being one of these factors. When using Edge, open a page and press the F12 key to access the developer settings.
Select the “Emulation” tab and look for the Sergeant string list.” Here you can choose to make Edge mimic the browser of your choice. Just as with Edge, Chrome has an useragentchange within the developer settings, although it is a lot more complicated to access.
From there click “Tools” and then “Developer Options.” You can also easily access this via the key combination of Ctrl + Shift + I. As you can see below, there will be an option to change the user agent by unpicking the “Select automatically” box.
A warning will appear, but it is quite safe to proceed, providing you don’t change settings or flags without due care and attention. If you don’t fancy the idea of messing with a browser’s settings, then there are some add-ons and extensions that will do the job for you.
It is currently, at the time of writing this article, a featured extension from Firefox, so that may put to rest some concerns that users may have. Matthew Muller Matt has worked in the tech industry for many years and is now a freelance writer.
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