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49-447: Prototype provides various functions for developing JavaScript applications. The features range from programming shortcuts to major functions for dealing with XMLHttpRequest . Prototype also provides library functions to support classes and class-based objects. In JavaScript, object creation is prototype -based instead: an object creating function can have a prototype property, and any object assigned to that property will be used as

98-866: A browser war with Netscape. On the JavaScript front, Microsoft created its own interpreter called JScript . Microsoft first released JScript in 1996, alongside initial support for CSS and extensions to HTML . Each of these implementations was noticeably different from their counterparts in Netscape Navigator . These differences made it difficult for developers to make their websites work well in both browsers, leading to widespread use of "best viewed in Netscape" and "best viewed in Internet Explorer" logos for several years. Brendan Eich later said of this period: "It's still kind of

147-543: A graphical user interface , Mosaic , was released in 1993. Accessible to non-technical people, it played a prominent role in the rapid growth of the early World Wide Web . The lead developers of Mosaic then founded the Netscape corporation, which released a more polished browser, Netscape Navigator , in 1994. This quickly became the most-used. During these formative years of the Web, web pages could only be static, lacking

196-523: A sidekick language. It's considered slow or annoying. People do pop-ups or those scrolling messages in the old status bar at the bottom of your old browser ." In November 1996, Netscape submitted JavaScript to Ecma International , as the starting point for a standard specification that all browser vendors could conform to. This led to the official release of the first ECMAScript language specification in June 1997. The standards process continued for

245-542: A Navigator beta in September 1995, the name was changed to JavaScript for the official release in December. The choice of the JavaScript name has caused confusion, implying that it is directly related to Java. At the time, the dot-com boom had begun and Java was a popular new language, so Eich considered the JavaScript name a marketing ploy by Netscape. Microsoft debuted Internet Explorer in 1995, leading to

294-399: A browser-based application to send requests to the server after page loading is complete, and receive information back. XMLHttpRequest is a component of Ajax programming . Prior to Ajax, hyperlinks and form submissions were the primary mechanisms for interacting with the server, often replacing the current page with another one. The concept behind XMLHttpRequest was conceived in 2000 by

343-418: A database query to return information. The notable standalone runtimes are Node.js , Deno , and Bun . The following features are common to all conforming ECMAScript implementations unless explicitly specified otherwise. JavaScript supports much of the structured programming syntax from C (e.g., if statements, while loops, switch statements, do while loops, etc.). One partial exception

392-436: A few years, with the release of ECMAScript 2 in June 1998 and ECMAScript 3 in December 1999. Work on ECMAScript 4 began in 2000. However, the effort to fully standardize the language was undermined by Microsoft gaining an increasingly dominant position in the browser market. By the early 2000s, Internet Explorer 's market share reached 95%. This meant that JScript became the de facto standard for client-side scripting on

441-539: A prototype for the objects created with that function. The Prototype framework is not to be confused with this language feature. The dollar function , $ (), can be used as shorthand for the getElementById function. To refer to an element in the Document Object Model (DOM) of an HTML page, the usual function identifying an element is: The $ () function reduces the code to: The $ () function can also receive an element as parameter and will return, as in

490-570: A specified amount of time. In the early development of the World Wide Web , it was found possible to breach users' security by the use of JavaScript to exchange information from one web site with that from another less reputable one. All modern browsers therefore implement a same origin policy that prevents many such attacks, such as cross-site scripting . XMLHttpRequest data is subject to this security policy, but sometimes web developers want to intentionally circumvent its restrictions. This

539-452: A stand-alone JavaScript runtime system. As of 2018, Node had been used by millions of developers, and npm had the most modules of any package manager in the world. The ECMAScript draft specification is currently maintained openly on GitHub , and editions are produced via regular annual snapshots. Potential revisions to the language are vetted through a comprehensive proposal process. Now, instead of edition numbers, developers check

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588-827: A variety of other software systems, both for server-side website deployments and non-browser applications . Initial attempts at promoting server-side JavaScript usage were Netscape Enterprise Server and Microsoft 's Internet Information Services , but they were small niches. Server-side usage eventually started to grow in the late 2000s, with the creation of Node.js and other approaches . Electron , Cordova , React Native , and other application frameworks have been used to create many applications with behavior implemented in JavaScript. Other non-browser applications include Adobe Acrobat support for scripting PDF documents and GNOME Shell extensions written in JavaScript. JavaScript has been used in some embedded systems , usually by leveraging Node.js. A JavaScript engine

637-520: A white paper in which he coined the term Ajax and described a set of technologies, of which JavaScript was the backbone, to create web applications where data can be loaded in the background, avoiding the need for full page reloads. This sparked a renaissance period of JavaScript, spearheaded by open-source libraries and the communities that formed around them. Many new libraries were created, including jQuery , Prototype , Dojo Toolkit , and MooTools . Google debuted its Chrome browser in 2008, with

686-530: Is scoping : originally JavaScript only had function scoping with var ; block scoping was added in ECMAScript 2015 with the keywords let and const . Like C, JavaScript makes a distinction between expressions and statements . One syntactic difference from C is automatic semicolon insertion , which allow semicolons (which terminate statements) to be omitted. JavaScript is weakly typed , which means certain types are implicitly cast depending on

735-494: Is a high-level , often just-in-time compiled language that conforms to the ECMAScript standard. It has dynamic typing , prototype-based object-orientation , and first-class functions . It is multi-paradigm , supporting event-driven , functional , and imperative programming styles . It has application programming interfaces (APIs) for working with text, dates, regular expressions , standard data structures , and

784-413: Is a programming language and core technology of the Web , alongside HTML and CSS . 99% of websites use JavaScript on the client side for webpage behavior. Web browsers have a dedicated JavaScript engine that executes the client code . These engines are also utilized in some servers and a variety of apps . The most popular runtime system for non-browser usage is Node.js . JavaScript

833-455: 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 and Web IDL bindings. However,

882-487: Is by far the most-used. Other notable ones include Angular , Bootstrap , Lodash , Modernizr , React , Underscore , and Vue . Multiple options can be used in conjunction, such as jQuery and Bootstrap. However, the term "Vanilla JS" was coined for websites not using any libraries or frameworks at all, instead relying entirely on standard JavaScript functionality. The use of JavaScript has expanded beyond its web browser roots. JavaScript engines are now embedded in

931-662: Is now the de facto standard in all the major browsers, including Mozilla's Gecko layout engine (2002), Safari 1.2 (2004) and Opera 8.0 (2005). The World Wide Web Consortium (W3C) published a Working Draft specification for the XMLHttpRequest object on April 5, 2006. On February 25, 2008, the W3C published the Working Draft Level 2 specification. Level 2 added methods to monitor event progress, allow cross-site requests, and handle byte streams. At

980-482: Is processed. Custom header fields can be added to the request to indicate how the server should fulfill it, and data can be uploaded to the server by providing it in the "send" call. The response can be parsed from the JSON format into a readily usable JavaScript object, or processed gradually as it arrives rather than waiting for the entire text. The request can be aborted prematurely or set to fail if not completed in

1029-572: Is sometimes due to the legitimate use of subdomains as, for example, making an XMLHttpRequest from a page created by foo.example.com for information from bar.example.com will normally fail. Various alternatives exist to circumvent this security feature, including using JSONP , Cross-Origin Resource Sharing (CORS) or alternatives with plugins such as Flash or Silverlight (both now deprecated). Cross-origin XMLHttpRequest

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1078-529: Is specified in W3C's XMLHttpRequest Level 2 specification. Internet Explorer did not implement CORS until version 10. The two previous versions (8 and 9) offered similar functionality through the XDomainRequest (XDR) API. CORS is now supported by all modern browsers (desktop and mobile). The CORS protocol has several restrictions, with two models of support. The simple model does not allow setting custom request headers and omits cookies . Further, only

1127-552: Is the dominant client-side scripting language of the Web, with 99% of all websites using it for this purpose. Scripts are embedded in or included from HTML documents and interact with the DOM . All major web browsers have a built-in JavaScript engine that executes the code on the user's device. Over 80% of websites use a third-party JavaScript library or web framework as part of their client-side scripting. jQuery

1176-475: The Ajax object to abstract the different browsers. It has two main methods: Ajax.Request() and Ajax.Updater() . There are two forms of the Ajax object. Ajax.Request returns the raw XML output from an AJAX call, while the Ajax.Updater will inject the return inside a specified DOM object. The Ajax.Request below finds the current values of two HTML form input elements, issues an HTTP POST request to

1225-450: The Document Object Model (DOM). The ECMAScript standard does not include any input/output (I/O), such as networking , storage , or graphics facilities. In practice, the web browser or other runtime system provides JavaScript APIs for I/O. Although Java and JavaScript are similar in name, syntax , and respective standard libraries , the two languages are distinct and differ greatly in design. The first popular web browser with

1274-516: The Firefox browser. Firefox was well received by many, taking significant market share from Internet Explorer. In 2005, Mozilla joined ECMA International, and work started on the ECMAScript for XML (E4X) standard. This led to Mozilla working jointly with Macromedia (later acquired by Adobe Systems ), who were implementing E4X in their ActionScript 3 language, which was based on an ECMAScript 4 draft. The goal became standardizing ActionScript 3 as

1323-511: The V8 JavaScript engine that was faster than its competition. The key innovation was just-in-time compilation (JIT), so other browser vendors needed to overhaul their engines for JIT. In July 2008, these disparate parties came together for a conference in Oslo . This led to the eventual agreement in early 2009 to combine all relevant work and drive the language forward. The result was

1372-402: The promise construct to simplify asynchronous logic. Browsers have since implemented the alternative fetch() interface to achieve the same functionality as XHR using promises instead of callbacks. Fetch is also standardized by WHATWG. JavaScript This is an accepted version of this page JavaScript ( / ˈ dʒ ɑː v ə s k r ɪ p t / ), often abbreviated as JS ,

1421-870: The DOM. There are plans to change this in the next major version of the library. In April 2010, blogger Juriy 'kangax' Zaytsev (of Prototype Core) described at length the problems that can follow from monkey patching new methods and properties into the objects defined by the W3C DOM. These ideas echo thoughts published in March 2010 by Yahoo! developer Nicholas C. Zakas They have been summarized as follows By 2008, specific issues with using DOM-extension methods in older versions of Prototype, combined with newer versions of current browsers, were already being documented. Rather than adding new methods and properties to pre-existing 'host' DOM objects such as Element , like element.hide() ,

1470-514: The ECMAScript 5 standard, released in December 2009. Ambitious work on the language continued for several years, culminating in an extensive collection of additions and refinements being formalized with the publication of ECMAScript 6 in 2015. The creation of Node.js in 2009 by Ryan Dahl sparked a significant increase in the usage of JavaScript outside of web browsers. Node combines the V8 engine, an event loop , and I/O APIs , thereby providing

1519-558: The HEAD, GET and POST request methods are supported, and POST only allows the following MIME types: "text/plain", "application/x-www-urlencoded" and " multipart/form-data ". Only "text/plain" was initially supported. The other model detects when one of the non-simple features are requested and sends a pre-flight request to the server to negotiate the feature. Program flow using asynchronous XHR callbacks can present difficulty with readability and maintenance. ECMAScript 2015 (ES6) added

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1568-477: The United States. The trademark was originally issued to Sun Microsystems on 6 May 1997, and was transferred to Oracle when they acquired Sun in 2009. A letter was circulated in September 2024, spearheaded by Ryan Dahl , calling on Oracle to free the JavaScript trademark . Brendan Eich the original creator of JavaScript, was among the over 14,000 signatories who supported the initiative. JavaScript

1617-405: The Web. Microsoft initially participated in the standards process and implemented some proposals in its JScript language, but eventually it stopped collaborating on ECMA work. Thus ECMAScript 4 was mothballed. During the period of Internet Explorer dominance in the early 2000s, client-side scripting was stagnant. This started to change in 2004, when the successor of Netscape, Mozilla , released

1666-426: The ability to import scripts. JavaScript is a single- threaded language. The runtime processes messages from a queue one at a time, and it calls a function associated with each new message, creating a call stack frame with the function's arguments and local variables . The call stack shrinks and grows based on the function's needs. When the call stack is empty upon function completion, JavaScript proceeds to

1715-527: The capability for dynamic behavior after the page was loaded in the browser. There was a desire in the flourishing web development scene to remove this limitation, so in 1995, Netscape decided to add a programming language to Navigator. They pursued two routes to achieve this: collaborating with Sun Microsystems to embed the Java language, while also hiring Brendan Eich to embed the Scheme language. The goal

1764-584: The developers of Microsoft Outlook . The concept was then implemented within the Internet Explorer 5 browser (2001). However, the original syntax did not use the XMLHttpRequest identifier . Instead, the developers used the identifiers ActiveXObject("Msxml2.XMLHTTP") and ActiveXObject("Microsoft.XMLHTTP") . As of Internet Explorer 7 (2006), all browsers support the XMLHttpRequest identifier. The XMLHttpRequest identifier

1813-507: The end of 2011, the Level 2 specification was absorbed into the original specification. At the end of 2012, the WHATWG took over development and maintains a living document using Web IDL . Generally, sending a request with XMLHttpRequest has several programming steps. Aside from these general steps, XMLHttpRequest has many options to control how the request is sent and how the response

1862-497: The new ECMAScript 4. To this end, Adobe Systems released the Tamarin implementation as an open source project. However, Tamarin and ActionScript 3 were too different from established client-side scripting, and without cooperation from Microsoft , ECMAScript 4 never reached fruition. Meanwhile, very important developments were occurring in open-source communities not affiliated with ECMA work. In 2005, Jesse James Garrett released

1911-414: The next message in the queue. This is called the event loop , described as "run to completion" because each message is fully processed before the next message is considered. However, the language's concurrency model describes the event loop as non-blocking : program I/O is performed using events and callback functions . This means, for example, that JavaScript can process a mouse click while waiting for

1960-409: The operation used. Values are cast to strings like the following: Values are cast to numbers by casting to strings and then casting the strings to numbers. These processes can be modified by defining toString and valueOf functions on the prototype for string and number casting respectively. JavaScript has received criticism for the way it implements these conversions as the complexity of

2009-437: The previous example, a prototype extended object. Building on the $ () function: the $ F() function returns the value of the requested form element. For a 'text' input, the function will return the data contained in the element. For a 'select' input element, the function will return the currently selected value. The dollar dollar function is Prototype's CSS Selector Engine . It returns all matching elements, following

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2058-465: The properties of the second object to the first one simulating inheritance. The combined object is also returned as a result from the function. As in the example above, the first parameter usually creates the base object, while the second is an anonymous object used solely for defining additional properties. The entire sub-class declaration happens within the parentheses of the function call. Unlike other JavaScript libraries like jQuery , Prototype extends

2107-437: The rules can be mistaken for inconsistency. For example, when adding a number to a string, the number will be cast to a string before performing concatenation, but when subtracting a number from a string, the string is cast to a number before performing subtraction. Often also mentioned is {} + [] resulting in 0 (number). This is misleading: the {} is interpreted as an empty code block instead of an empty object, and

2156-459: The same rules as a selector in a CSS stylesheet. For example, if you want to get all <a> elements with the class "pulsate", you would use the following: This returns a collection of elements. If you are using the script.aculo.us extension of the core Prototype library, you can apply the "pulsate" (blink) effect as follows: In an effort to reduce the amount of code needed to run a cross-browser XMLHttpRequest function, Prototype provides

2205-569: The server with those element name/value pairs, and runs a custom function (called showResponse below) when the HTTP response is received from the server: Prototype also adds support for more traditional object-oriented programming. The Class.create() method is used to create a new class. A class is then assigned a prototype which acts as a blueprint for instances of the class. Extending another class: The framework function Object.extend(dest, src) takes two objects as parameters and copies

2254-401: The solution to these issues is to provide wrapper objects around these host objects and implement the new methods on these. jQuery is such a wrapper object in the library of that name. XMLHttpRequest XMLHttpRequest ( XHR ) is an API in the form of a JavaScript object whose methods transmit HTTP requests from a web browser to a web server . The methods allow

2303-436: The status of upcoming features individually. The current JavaScript ecosystem has many libraries and frameworks , established programming practices, and substantial usage of JavaScript outside of web browsers. Plus, with the rise of single-page applications and other JavaScript-heavy websites, several transpilers have been created to aid the development process. "JavaScript" is a trademark of Oracle Corporation in

2352-506: The use of JavaScript engines is not limited to browsers; for example, the V8 engine is a core component of the Node.js runtime system . A JavaScript engine must be embedded within a runtime system (such as a web browser or a standalone system) to enable scripts to interact with the broader environment. The runtime system includes the necessary APIs for input/output operations, such as networking , storage , and graphics , and provides

2401-399: Was a "language for the masses", "to help nonprogrammers create dynamic, interactive Web sites ". Netscape management soon decided that the best option was for Eich to devise a new language, with syntax similar to Java and less like Scheme or other extant scripting languages . Although the new language and its interpreter implementation were called LiveScript when first shipped as part of

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