JScript is the scripting language used in Microsoft's Internet Explorer.

JScript is implemented as a Windows Script engine. JScript was first supported in Internet Explorer 3.0 browser released in August 1996. The typical file extension of JScript source code files is .js.

In 2004-2006, the most recent version of JScript was JScript .NET, which was based on the yet-unfinished edition 4 of the ECMAScript standard, and can be compiled for the Microsoft .NET platform. JScript.NET, which added several new features to ECMAScript ed. 3, such as optional static type annotations, appears no longer to be actively developed.