Proofing: add "preview" option to preview changes

[epicfaace]

trafficstars

A "preview" option should preview changes and show a diff before you save those changes.

[akprasad]

What kinds of changes would you want to preview?

[shreevatsa]

I too think, like Wikipedia, it would be good have the option to see what change you're making (the state of the proofread text before and after your change), just before you hit Save.

[akprasad]

To my mind, that feature is useful for Wikipedia because users also make formatting changes. What would or could our preview show here?

[shreevatsa]

Ashwin may have better examples, but for example if I suspect that I may have randomly typed something by mistake (cat/toddler came to the keyboard?), then it would be helpful to double-check before submitting. Just like how I always run git diff before git commit :-)

Showing the diff after the Save is an acceptable substitute too.

(Oh BTW just realized you may be talking about "Preview" v/s "Diff" — yeah not "rendered" preview as on Wikipedia; I was just using them interchangeably, in the sense of "preview changes" == "view diff".)

[epicfaace]

Yes -- double-checking before submitting. Sometimes I make various changes to a page, and I don't remember what all I did -- and I'd like to review them to ensure I didn't mess up anywhere -- before submitting. It's non-ideal to have to save the changes before you can view the diff.

[akprasad]

Ah I see -- yes, that's a great suggestion. I'm happy to receive a PR for this!