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In context: Home windows has included a proprietary JavaScript engine for the reason that launch of Web Explorer 3.0 practically 30 years in the past. Technically, JScript is Microsoft’s personal dialect of the ECMAScript/JavaScript commonplace. It was used not solely by the Web Explorer browser but additionally by third-party purposes as a standalone scripting engine for Home windows.
Microsoft formally retired JScript years in the past, together with correct help for the unique Web Explorer browser. Nonetheless, the JScript engine nonetheless lingers in trendy Home windows installations, posing potential safety dangers to the PC ecosystem. In an effort to deal with these considerations, Microsoft is now changing the legacy JScript engine with a safer runtime known as JScript9Legacy.
The brand new runtime is an Energetic Scripting engine launched completely with Home windows 11 model 24H2. It’s based mostly on the JScript “Chakra” engine that debuted with Web Explorer 9. Whereas IE has been discontinued, JavaScript scripting stays supported within the newest Home windows editions for compatibility and particular enterprise use circumstances.
Microsoft just lately introduced that the JScript9Legacy engine is now enabled by default in Home windows 11 24H2. It’s going to deal with all scripting processes and operations beforehand executed utilizing the unique JScript engine. Constructed on JScript9, this up to date engine delivers improved efficiency and enhanced safety features.
The brand new engine was designed to supply higher compatibility with trendy net requirements, the identical elementary cause Microsoft deserted Web Explorer and JScript in favor of the Edge/Chromium platform. JScript9Legacy goals to assist scripting professionals mitigate safety dangers related to cross-site scripting and different web-based assaults.
New safety features in JScript9Legacy embody improved dealing with of JavaScript objects and stricter execution insurance policies. These enhancements are meant to make it tougher for malicious scripts to take advantage of vulnerabilities and achieve management over Home windows methods. Microsoft believes the brand new engine will present a safer scripting atmosphere for PC customers, though the corporate continues to launch month-to-month safety updates to deal with XSS and different script-based threats.
JScript9Legacy will exchange the legacy JScript engine in Home windows 11 model 24H2 and newer builds. All scripting duties beforehand dealt with by JScript will robotically transition to the brand new jscript9Legacy.dll runtime. No consumer motion is required, and Microsoft doesn’t anticipate any detrimental affect on present scripting workflows.
Nonetheless, the corporate acknowledges that unexpected compatibility points should still come up. To accommodate enterprise customers with particular wants, Microsoft is providing a rollback choice to the unique JScript engine. Prospects requiring help can request detailed directions by means of the Home windows Providers Hub.
