chore: significant speedup by skipping filing-cabinet ts-config parsing

[FauxFaux]

madge is annoyingly slow for us. This patch takes it from 1m26s to 7s (>10x speedup), for ~2,000 typescript files.

filing-cabinet, which the dependency walking stuff runs internally, runs this incredibly slow config loader in the loop. Instead, do it at the top, and pass the object in, which it already supports.

Config loading mostly copied from: https://github.com/dependents/node-filing-cabinet/blob/74185e06edbbcbb3062265946adbada9b5584999/index.js#L199-L201

This is essentially just doing JSON.parse(fs.loadFileSync(..)), aiui. except it copes with some typescript weirdness (e.g. comments in the json).

I'm not sure that's really the best place to translate the config object, but the program.tsConfig above seems not to be hit? I don't really understand why.

[pahen]

Sweet! I don't use TypeScript myself so I didn't experienced this issue. The fix looks good but I think this should probably be fixed in https://github.com/dependents/node-dependency-tree/blob/master/lib/Config.js instead to take benefit of the improvement when not using Madge too.

[pahen]

Should work now if you do a fresh install of Madge @FauxFaux

[pahen]

Should work now if you do a fresh install of Madge @FauxFaux

[FauxFaux]

This change, which we're still running, offers a significant speedup still; from ~21s -> ~9s. (we have more typescript now!).

I am not sure why.

[FauxFaux]

I think it's because we call dependencyTree 2,000 times still:

madge/lib/tree.js

Line 126 in 64364bf

tsConfig: this.config.tsConfig,

..and each time it must compile the config. It is no longer compiling the config tens of times, but there's still 2,000 unnecessary compiles for us.

[pahen]

Thanks for your effort! Merged and published in Madge v3.9.1