Plots.resize returns a Promise

[aleburato]

As the resize operation will modify the size of the plot only after a
timeout, if you call resize and then immediately do something based on
the current plot size, you'll get the "old" size. This fixes it.

[etpinard]

Thanks for the PR. Nice find! 🍻

A few things will need to happen before we merge this in:

• you'll need to lint (or un-lint depending on your preferences). Make sure npm run lint output no errors. Also, plotly.js is a fan of if() without spaces which is not enforced yet via npm run lint.
• we'll need to add some tests in https://github.com/plotly/plotly.js/blob/master/test/jasmine/tests/plot_promise_test.js . Let us know if you any questions on how to go about this.

[aleburato]

Heh! I'm so new to this (I mean git, not Javascript or developing in general).

I didn't notice the style guides, and unfortunately I created the pull request just before leaving the office. I'll edit the code to make it compliant to the style guide and submit a new pull request. Is it OK?

[etpinard]

You can simply push new commits to your promise-from-resize branch and these commits will automatically show up in this PR.

[aleburato]

Done. One last question: I have installed eslint in my editor (VS Code) and it correctly picks up plotly's .eslintrc. However, it complains about "Promise" not being defined (see: http://eslint.org/docs/rules/no-undef).
Adding a */global Promise*/comment in the plots.js file fixes the warning, but I guess that if you didn't do that already (and npm run lint is not complaining either), I'm missing something.

[etpinard]

I have installed eslint in my editor

You must be running version 2.0.x of eslint through your editor. Looks like they cleaned up some of their namespacings in v2.0.0 (see here). plotly.js is still using v1.x.x. to run npm run lint explaining the discrepancy.

So, don't worry about Promise warnings, we'll clean those up soon.

Your PR looks good, it's missing some tests though. Are you interested in adding some tests in https://github.com/plotly/plotly.js/blob/master/test/jasmine/tests/plot_promise_test.js ? If not, we'll take care of it.

[aleburato]

As this is my first time I'd prefer you to go ahead with the tests, so that i can see how it's done. Thanks!

[mdtusz]

We'll merge this in then apply some tests on top. Thanks for the contribution!