Add chart method for getting initial scale bounds

[MrJohz]

Based on the discussion in #584, this adds a new method, getInitialScaleBounds that returns an object mapping scale IDs to {min, max} values.

console.log(chart.getInitialScaleBounds());
// {
//    x: {min: 3, max: 8},
//    y: {min: -10, max: 10}
// }

I've added tests and type definitions. I couldn't see anywhere obvious to document this in the guide, but I think exporting it from index.d.ts at least adds some basic type doc stuff, right?

[LeeLenaleee]

Guess to keep it in line with the main chartjs docs it's best to create a sub cat under the developer section call it API and put it in there

https://www.chartjs.org/docs/master/developers/api.html

[kurkle]

Added a suggestion, but I did not try this - so it might not make sense.
Looks good to me. Wondering if a (additional?) higher level isZoomedOrPanned() (or something) would be a better API for this kind of use cases?

[MrJohz]

Guess to keep it in line with the main chartjs docs it's best to create a sub cat under the developer section call it API and put it in there

👍 Can do

Looks good to me. Wondering if a (additional?) higher level isZoomedOrPanned() (or something) would be a better API for this kind of use cases?

I can imagine getting the original bounds will still be useful, but you're right, having the higher level API there as well would also be useful. I'll have a go at adding that as well, although I might only get round to that on Monday or something.

[life-of-e]

A isZoomedOrPanned() might be helpful, it may also address my problem where trying to reset all of the charts on a page at once breaks (see my Discussion #583)

[MrJohz]

I've added documentation for all methods added on the Chart.js instance. I also noticed while doing that, that the zoom method had the wrong Typescript types, so I fixed that as well.

@kurkle, does that work for you?

[kurkle]

Nice work, thank you!

I've requested a review from @etimberg too, lets see if he has any notes

[kurkle]

Looks like there are some linting errors (due to the fixed types and incorrect usage in the exports.ts)

[test-lint] [lint-tsc] types/tests/exports.ts(53,60): error TS2345: Argument of type 'true' is not assignable to parameter of type '"normal" | "none" | "hide" | "show" | "active" | "reset" | "resize" | "zoom"'.

[MrJohz]

I think I've fixed that issue, there was also a linting error in the documentation somewhere that I believe I've fixed now as well.

[kurkle]

coveralls.io is in maintenance currently, that's why the CI fails. I'd expect it to become available later today.

[MrJohz]

@kurkle, looks like it's back up and running again. Is there an easy way to rerun the failed jobs, or do I need to push a new commit or something?