JavaScript fundamentals

As the name implies, the ArcGIS API for JavaScript requires that you use the JavaScript language when developing your application. There are some fundamental JavaScript programming concepts that you will need to know before starting to build your application.

JavaScript is a lightweight scripting language that is embedded in all modern web browsers. Although JavaScript can certainly exist outside the web browser environment in other applications, it is best known for its integration with web applications.

All modern web browsers including Chrome, Firefox, Safari, and Edge have JavaScript embedded. The use of JavaScript in web applications enables the creation of dynamic applications that do not require round trips to the server to fetch data, and thus the applications are more responsive and feel like native applications. However, JavaScript can submit requests to the server for more (or more up-to-date) information, and is a core technology in the AJAX (Asynchronous JavaScript and XML) stack.