cscript jscript JSON


This is a very very (very!!!) strange problem.

I have this JSCRIPT that runs on windows XP and 7 using dos CSCRIPT in a file called testJSON.js.

if ( ! this.JSON ) WScript.Echo("JSON DOESN'T EXISTS");

And, well, the message appear, but is an unexpected behavior of JSCRIPT because JSON (as the MSDN documentation says) is one of the default object in the JSCRIPT 5.8 and my system on Windows 7 runs exactly JSCRIPT 5.8.

Now, I have temporary solved this problem (in a little complex script) by creating a new text file and MANUALLY composing a valid JSON string (and, obviously this makes everything works fine even if the system doesn't have the JSCRIPT 5.8 as requested for JSON) but I like to know two things mainly:

1st Why I can't use the JSON object even if my JSCRIPT version is the one that supports that object?

2nd I have read something about the "enabling" of the JSON (and other) unavailable object in my JSCRIPT environment, but all examples is for C# and I like to know if some equivalent code for JSCRIPT exists or not.


Answers:


Why I can't use the JSON object even if my JSCRIPT version is the one that supports that object?

According to MSDN, Windows Script Host uses the JScript 5.7 feature set by default for backward compatibility. The JScript 5.8 feature set is only used in Internet Explorer in the IE8+ Standards document modes.

You have the following options:

  1. Include json2.js in your script. See this question for options for including external scripts in JScript scripts.

  2. Modify the registry to expose IE9's JScript engine to Windows Script Host. UPD: This solution uses IE's JScript DLLs, but doesn't activate the 5.8 feature set.

  3. Create a JScript execution host programmatically using the Active Script interfaces and use IActiveScriptProperty::SetProperty to force the JScript 5.8 feature set (SCRIPTLANGUAGEVERSION_5_8). Here's a C++ example.

I have read something about the "enabling" of the JSON (and other) unavailable object in my JSCRIPT environment, but all examples is for C# and I like to know if some equivalent code for JSCRIPT exists or not.

Custom script execution hosts can be created only using languages with proper COM support, such as C++, C# etc. JScript can't be used for that, because, for example, it doesn't support out parameters.