Google Closure Tools is a set of tools to help developers build rich

web application A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serv ...

s with

JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...

. It was developed by

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

for use in their

s such as

Gmail Gmail is a free email service provided by Google. As of 2019, it had 1.5 billion active users worldwide. A user typically accesses Gmail in a web browser or the official mobile app. Google also supports the use of email clients via the POP and ...

, Google Docs and

Google Maps Google Maps is a web mapping platform and consumer application offered by Google. It offers satellite imagery, aerial photography, street maps, 360° interactive panoramic views of streets ( Street View), real-time traffic conditions, and rou ...

Closure Compiler

The Closure Compiler is a tool for making JavaScript downloads run faster, at the expense of human readability. It does not compile from JavaScript to

machine code In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a ve ...

, but rather compiles from JavaScript to more efficient JavaScript. It parses JavaScript, analyzes it, removes dead code and rewrites and minifies what is left. It also checks syntax,

variable Variable may refer to: * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...

references, and

types Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type In computer science and computer programming, a data type (or simply type) is a set of possible values and a set of allo ...

and warns about common JavaScript pitfalls. It supports transpiling modern

ECMAScript ECMAScript (; ES) is a JavaScript standard intended to ensure the interoperability of web pages across different browsers. It is standardized by Ecma International in the documenECMA-262 ECMAScript is commonly used for client-side scripting o ...

code to ECMAScript 5, so that programmers can write JavaScript that uses those features, and run it in

browsers Browse, browser or browsing may refer to: Programs * Web browser, a program used to access the World Wide Web *Code browser, a program for navigating source code * File browser or file manager, a program used to manage files and related objects * ...

or other environments that do not yet support them. (the Traceur Compiler is another Google project that supports transpiling ES6 to ES3.)

CLI based tools

Tool set provide a

command line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

tools used to optimize and compile .js files: *

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...

-based application run from shell which compiles a list of specified JavaScript files * npm package google-closure-compiler which provides as optional dependencies three compilers: native (binary executable), JAVA and JavaScript-based one; which are installed at once.

Others

*Interactively in the browser: **The Closure Compiler service website provides a form for a user to input a URL pointing to a JavaScript source or enter JavaScript source code in a text box. The website will display with the ''optimized JavaScript'' on right side for the user to copy. *HTTP POST API: **The Closure Compiler server accepts HTTP POST requests. Parameters include the string of JavaScript to be optimized (or a URL pointing to it), the optimization level, whether to include errors and warnings, and the output format (JSON, XML, or text). The Closure compiler also supports

type checking In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a type to every "term" (a word, phrase, or other set of symbols). Usually the terms are various constructs of a computer progra ...

via type annotations that must be written in

JSDoc JSDoc is a markup language used to annotate JavaScript source code files. Using comments containing JSDoc, programmers can add documentation describing the application programming interface of the code they're creating. This is then processed ...

comments.

Ecosystem

Programming languages that transpile to JavaScript benefit from Closure Tools. For example, Closure Compiler helps to make

ClojureScript Clojure (, like ''closure'') is a dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. The current development process is com ...

practical by making the compiled JavaScript code more efficient.

Closure Library

The Closure Library is a

JavaScript library A JavaScript library is a library of pre-written JavaScript code that allows for easier development of JavaScript-based applications, especially for AJAX and other web-centric technologies. Libraries With the expanded demands for JavaScript, an ea ...

, written specifically to take advantage of the Closure Compiler, based on a modular architecture. It provides

cross-browser Cross-browser compatibility is the ability of a website or web application to function across different Web browser, browsers and Fault tolerance, degrade gracefully when browser features are absent or lacking. History Background The history ...

functions for

DOM Dom or DOM may refer to: People and fictional characters * Dom (given name), including fictional characters * Dom (surname) * Dom La Nena (born 1989), stage name of Brazilian-born cellist, singer and songwriter Dominique Pinto * Dom people, an et ...

manipulations and

events Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of ev ...

Ajax Ajax may refer to: Greek mythology and tragedy * Ajax the Great, a Greek mythological hero, son of King Telamon and Periboea * Ajax the Lesser, a Greek mythological hero, son of Oileus, the king of Locris * ''Ajax'' (play), by the ancient Gree ...

and JSON, as well as more high-level objects such as

User Interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...

widgets and Controls.

Closure Templates

Closure Templates are a templating system for dynamically generating

HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaSc ...

in both

and

. Because the language was apparently referred to as "Soy" internal to Google, and "Soy" remains in some of the documentation and classes, sometimes Closure Templates are referred to as "Soy Templates".

Closure Stylesheets

This is a compiler which provides an extended version of CSS, which is compiled down to ordinary CSS. Internally in Google, this extended version of CSS is referred to as GSS.

References

External links

*
Package for TYPO3 Flow
{{JavaScript 2009 software Free software programmed in Java (programming language) JavaScript libraries Web development software Closure Tools