Broken example for vm.runInDebugContext(code) #4862

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1. MylesBorins

   added

   docIssues and PRs related to Node.js documentation.Issues and PRs related to Node.js documentation.

   vmIssues and PRs related to the vm subsystem.Issues and PRs related to the vm subsystem.

   on Jan 25, 2016
2. MylesBorins commented on Jan 25, 2016

   

   MylesBorins

   on Jan 25, 2016

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   /cc @nodejs/documentation
3. bnoordhuis commented on Jan 25, 2016

   

   bnoordhuis

   on Jan 25, 2016

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   Oh, that's because you need to start the debugger first now before you have access to Debug.scripts(). I'd swap it out for a different example.
4. bnoordhuis commented on Jan 25, 2016

   

   bnoordhuis

   on Jan 25, 2016

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   Like this:

   > vm.runInDebugContext('Debug').findScript(process.exit).name
   'node.js'
   
   > vm.runInDebugContext('Debug').findScript(process.emit).name
   'events.js'
   
5. MylesBorins commented on Jan 25, 2016

   

   MylesBorins

   on Jan 25, 2016

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   @bnoordhuis can you share an example of running arbitrary in a vm context?

   I think I can get a test for #4819 by running some code in a debug context, but perhaps I am missing some... context (sorry couldn't help it).

   When I try something like

   const Debug = vm.runInDebugContext('var util = require("util");');
   

   I get

   undefined:1
   var util = require("util");
              ^
   ReferenceError: require is not defined
       at <anonymous>:1:12

   As the definition of runInDebugContext is vm.runInDebugContext(code) I thought I could feed arbitrary code. It appears that this context does not by default have access to all the node bits in the main context (this is a guess).

   I'll dig into the c++ and report back
6. bnoordhuis commented on Jan 25, 2016

   

   bnoordhuis

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   As the definition of runInDebugContext is vm.runInDebugContext(code) I thought I could feed arbitrary code. It appears that this context does not by default have access to all the node bits in the main context (this is a guess).

   That's correct. It's a clean slate JS VM with debugger bits but no node bits. It's similar to vm.runInNewContext(code) in that respect, except that doesn't even have debugger bits.
7. MylesBorins commented on Jan 25, 2016

   

   MylesBorins

   on Jan 25, 2016

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   @bnoordhuis ahhh. That makes a lot of sense. I'll dig into the debugger source and see how it sets up the environment. That is a bit out of scope for this issue though, so I'll try and put together a working example for VM and perhaps some documentation about the context
8. MylesBorins

   self-assigned this

   on Jan 25, 2016
9. yorickvP commented on May 14, 2016

   

   yorickvP

   on May 14, 2016

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   Did you figure out how to do it?
10. bnoordhuis

    closed this as completedin #6757on May 16, 2016
11. evanlucas

    added a commit that references this issue on May 17, 2016

    doc: update vm.runInDebugContext() example

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    688f563
12. MylesBorins

    added 2 commits that reference this issue on May 18, 2016

    doc: update vm.runInDebugContext() example

    ...

    a2339e4

    doc: update vm.runInDebugContext() example

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    50f02bd