Fix helper._calculatePadding return NaN causes Maximum Call Stack Size Exceeded

[duykhang53]

I encounter an issue that causes maximum call stack size exceeded in Chrome by using ng2-charts, found out that was in issue from this library.

The root cause from helpers.getStyle() inside helpers._calculatePadding() return an empty string, so parseInt() will result NaN that cause fitBoxes() recursive called infinitively.

[kurkle]

I'm curious, when does this happen?

[duykhang53]

It happens when the element is not yet attached to DOM, I think.

My Angular project place that <canvas> inside a <div> and later on it bind that <div> to DOM. It really weird that getComputedStyle() return an empty string for padding property.

[duykhang53]

[kurkle]

Another curiosity, does this change make it work alright?

[duykhang53]

Yes, of course!

[kurkle]

I suppose resize gets called again, when attached to DOM. What browser are you testing with and did you test any others?

[duykhang53]

I tested on Chrome, Firefox and Edge, it throws an exception in zone.js (Angular mechanism), I think. That causes the code for that component no further running.

fitBoxes() was called infinitely because width and height in updateDims() compare NaN to NaN (it always false). So the issue is from resize() call in constructor.

[kurkle]

#5955 is loosely related

[kurkle]

Why is this needed?

[duykhang53]

Similar to the dist folder, when you run npm pack, it will generate chart.js-<version>.tgz which use for local npm install. It may use for testing when the package is not uploaded to npmjs.

[duykhang53]

Thanks for the merge, btw can you guys update npm version tag?

https://travis-ci.org/chartjs/Chart.js/builds/628564087#L5259