How do you change the value of a local variable using Chrome's dev tools?

Question

I'm using Chrome's (v21) dev tools to debug a large javascript application. While stepping through the code, I'd like to change the value of a local (function scope) variable. How do I do this?

I've tried:

1. Clicking on the variable in the "Scope" window and editing it, hitting Enter afterward. The value changes in the Scope window as expected, but when I step to the next line, the variable then reverts back to its old value.
2. Typing "variable = 123" in the console. After I hit Enter, the console "result" is the value I entered, but the variable itself does not change in value. If I then enter "variable" and hit Enter, the console returns the original value; the Scope window also shows the original value still.

Again, this is a local, function-scoped variable, and the current line of execution is within the same scope where the variable was defined.

This other question is essentially a duplicate, but hasn't elicited any useful answers (maybe because it's poorly written).

Pforzheim

+1 - I've not run into a situation where I've needed to do this, but it's true, I would have expected it to work like the immediate window in Visual Studio. Can verify that Chrome v22 is the same. Have you looked through the Chrome bug reports to see if there's something along these lines reported? I'm sure it isn't a 'bug' per se... more just 'non-intuitive behavior' – Pentylenetetrazol

Using a different variation of keywords, I was able to find another question that answers this. Disappointing that you cannot do this in Chrome. :( – Pforzheim

Alas, you cannot. I'm sure there's already an open issue about that... Since a very long time. – Devonne

I'm surprised that this is not possible in Chrome dev tools. I do this in Firebug all the time. – Implead

Filed a bug report for this. – Pforzheim

Already implemented in V8: Issue 2399 Now Chromium's Developer Tools need to be updated: Issue 124206 – Arthur

Answer 1

This apparently got fixed eventually. From the issue that @gabrielmaldi linked issue 124206:

Comment 29 by [email protected] on Wed, May 4, 2016, 3:19 PM EDT 51.0.2696.0 is the first [development] version that includes a build of v8 that incorporates a fix for this regression (v8 version 5.1.224 includes this fix, and 51.0.2696.0 targets v8 version 5.1.227.1).

Litharge

Answer 2

This feature is yet to be implemented. It is absolutely reasonable thing to do, hopefully it will be implemented soon in V8–protocol–devtools.

Tufted