Browser support, 5.7 and newer broken in older browsers

[spatialillusions]

maplibre-gl-js 5.7 and newer:

Couldn't find how old browsers that are supposed to be supported, but couldn't find anything in the release notes for 5.7 that it was supposed to break combability with older browsers.

Chrome 76:

Steps to Trigger Behavior

1. Try to load any maplibre example in an old browser such as Chrome 76
2. Trying out different versions shows that 5.6 works, but 5.7 won't work.

Expected Behavior

Maplibre loads as expected.

Actual Behavior

Maplibre won't load and we get an error in the console:

Uncaught SyntaxError: Unexpected token . maplibre-gl.js:44

(The unexpected token is the period, probably because somewhere in the code ?. is used.)

[HarelM]

Old versions support old browsers, new version support newer browser, we don't keep track of which features we introduce that old browsers do not support.

[spatialillusions]

I have looked into the root of the issue, and I have found the two external libraries that causes the code to break in old browsers.

The first one is easy, it is maplibre/vt-pbf and the only thing needed there is to set target in the tsconfig file to be ES20216 in the same way as maplibre has.

The other external library is maplibre/mlt and that is a bit trickier since the code relies heavily on BigInt support and that is harder to get around. How ever the target version for mlt should be possible to reduce down to ES2020.

(I added babel just to try it out and was able to build mlt for chrome 76 that has support for BigInt, but lacks the support conditional chaining using ?. )

[HarelM]

I would very much like to avoid using babel. Can you explain why setting es2016 here in this repo isn't enough though?

[spatialillusions]

If I understand correctly, TypeScript target: ES2016 downlevels your TS, but @rollup/plugin-typescript by default does not transpile JS from node_modules. There might be a possibility that rollup can be configured in another way, but I haven't looked deeply into that.

Secondly, maplibre/mlt can't be transpiled into ES2016 since it relies on BigInt that isn't available in ES2016, the lowest maplibre/mlt can be transpiled into, without babel, is ES2020.

[HarelM]

Ahh, I see, that can explain some stuff that's been breaking lately.