fix: Add polyfill for use in browsers when qs.unescape is unavailable

[okdistribute]

In browser environments when using browserify, qs.unescape is not defined. Although this is a problem with the underlying querystring module not being up to date with node core, and not a problem with tilelive itself, there have been multiple attempts to update the querystring module without success. See the following issue threads: Gozala/querystring#20 (open since April 2017) and Gozala/querystring#6 (open since 2015)

[jingsam]

tilelive is not intended for been used in browser enviroment. So it maybe useless to add this polyfill

[okdistribute]

@jingsam it works perfectly fine in a browser environment with this polyfill.

[okdistribute]

Think this might be able to be merged?

[okdistribute]

OK I'm making a new package, tilelive-browser

[mapsam]

@Karissa sorry for the silence here. In general I think this is a great change, but I'm hesitant to flat-out say tilelive works in the browser (i.e. my frontend experience is limited and if we document that this works in browsers, that opens up a whole new path of issues in the future that we won't be able to effectively respond to). I like your idea of creating tilelive-browser 👍 - will gladly add that to the list of tilelive plugins in the README!

[jingsam]

I am very curious on the use cases that run tilelive in browsers.

[okdistribute]

Hey @jingsam, we built a user interface where users can select a bounding box they want to download in an interactive map. It will then download those tiles for them into a tar file, which is saved in the user's cache (so it can expand without memory limits). See https://github.com/digidem/tile-downloader and https://github.com/karissa/mapbox-download-ctrl/