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Proxy Auto-config
A proxy auto-config (PAC) file defines how web browsers and other user agents can automatically choose the appropriate proxy server (access method) for fetching a given URL. A PAC file contains a JavaScript function FindProxyForURL(url, host). This function returns a string with one or more access method specifications. These specifications cause the user agent to use a particular proxy server or to connect directly. Multiple specifications provide a fall-back when a proxy fails to respond. The browser fetches this PAC file before requesting other URLs. The URL of the PAC file is either configured manually or determined automatically by the Web Proxy Auto-Discovery Protocol. Context Modern web browsers implement several levels of automation; users can choose the level that is appropriate to their needs. The following methods are commonly implemented: * Automatic proxy selection: Specify a host-name and a port number to be used for all URLs. Most browsers allow you to specify ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Browser
A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on a range of devices, including desktops, laptops, tablets, and smartphones. In 2020, an estimated 4.9 billion people used a browser. The most used browser is Google Chrome, with a 65% global market share on all devices, followed by Safari with 18%. A web browser is not the same thing as a search engine, though the two are often confused. A search engine is a website that provides links to other websites. However, to connect to a website's server and display its web pages, a user must have a web browser installed. In some technical contexts, browsers are referred to as user agents. Function The purpose of a web browser is to fetch content from the World Wide Web or from local storage and display it on a user's device. This process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Port (computer Networking)
In computer networking, a port is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an operating system, a port is a logical construct that identifies a specific process or a type of network service. A port is identified for each transport protocol and address combination by a 16-bit unsigned number, known as the port number. The most common transport protocols that use port numbers are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). A port number is always associated with an IP address of a host and the type of transport protocol used for communication. It completes the destination or origination network address of a message. Specific port numbers are reserved to identify specific services so that an arriving packet can be easily forwarded to a running application. For this purpose, port numbers lower than 1024 identify the historically most commonly used services ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JavaScript Engine
A JavaScript engine is a software component that executes JavaScript code. The first JavaScript engines were mere interpreters, but all relevant modern engines use just-in-time compilation for improved performance. JavaScript engines are typically developed by web browser vendors, and every major browser has one. In a browser, the JavaScript engine runs in concert with the rendering engine via the Document Object Model. The use of JavaScript engines is not limited to browsers. For example, the V8 engine is a core component of the Node.js and Deno runtime systems. Since ECMAScript is the standardized specification of JavaScript, ECMAScript engine is another name for these engines. With the advent of WebAssembly, some engines can also execute this code in the same sandbox as regular JavaScript code. History The first JavaScript engine was created by Brendan Eich in 1995 for the Netscape Navigator web browser. It was a rudimentary interpreter for the nascent language Eich inven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNS Cache
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. The Domain Name System has been an essential component of the functionality of the Internet since 1985. The Domain Name System delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain. Network administrators may delegate authority over sub-domains of their allocated name space to other name servers. This mechanism provides distributed and fault-tolerant service and was designed to avoid a single large central da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
