# Missing expression evaluation in the DevTools console

**URL:** <https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977>\
**Category:** Developer Tools\
**Created:** [October 3, 2017, 5:15pm UTC](https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977 "2017-10-03T17:15:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![bruce.w\_H](https://avatars.discourse-cdn.com/v4/letter/b/a4c791/32.png) [@bruce.w\_H](https://discourse.mozilla.org/u/bruce.w_H)\
**Post date:** [October 3, 2017, 5:15pm UTC](https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977/1 "2017-10-03T17:15:37Z")

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Hello,

I really love Firefox Developer, I think it’s much sexier than Chrome, it’s dark theme is awesome, and there are some features unique to Firefox Developer like finding out the event triggered by a button right in the inspector markup view (this even works in React).

However I’m a little surprised to see that it’s missing expression evaluation in the console, in my current react project I can’t evaluate any expressions, neither in the scratchpad, I’m using webpack and I find myself using Chrome just for this feature, I’d additionally like to suggest showing the values of variables next to them in the debugger like IntelliJ and Chrome do.

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**Author:** ![Nicolas\_Chevobbe](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/nicolas_chevobbe/32/28203_2.png) [@Nicolas\_Chevobbe](https://discourse.mozilla.org/u/Nicolas_Chevobbe)\
**Post date:** [October 3, 2017, 5:36pm UTC](https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977/2 "2017-10-03T17:36:20Z")

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Hello Bruce, that’s very odd.  
What is your setup ? Could you hand us a link and some instructions on how to see the issue you’re facing ?

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**Author:** ![bruce.w\_H](https://avatars.discourse-cdn.com/v4/letter/b/a4c791/32.png) [@bruce.w\_H](https://discourse.mozilla.org/u/bruce.w_H)\
**Post date:** [October 3, 2017, 5:42pm UTC](https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977/3 "2017-10-03T17:42:54Z")

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Unfortunately it is a private repo and I can’t share it, but seeing your response makes me think that it is something particular to this project, I will try with another repo/project and test. Sometimes the UI also hangs and the buttons stop responding, again, this might be particular to my project, will try with other projects.

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**Author:** ![Nicolas\_Chevobbe](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/nicolas_chevobbe/32/28203_2.png) [@Nicolas\_Chevobbe](https://discourse.mozilla.org/u/Nicolas_Chevobbe)\
**Post date:** [October 4, 2017, 9:27am UTC](https://discourse.mozilla.org/t/missing-expression-evaluation-in-the-devtools-console/19977/4 "2017-10-04T09:27:53Z")

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It would be nice if we could figure out the issue with your project though.  
Are you using a specific library ?  
Are you using sourcemaps / a build process ?  
Do you have some CSP rules ?  
Do you use iframes, maybe sandboxed ?