Clarify README for tsx/jsx endings.

[NaridaL]

Fix #1178

[codecov]

Codecov Report

Merging #1179 (f4e38c4) into master (d2ccc5c) will decrease coverage by 0.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1179      +/-   ##
==========================================
- Coverage   79.74%   79.48%   -0.26%     
==========================================
  Files          12       12              
  Lines         780      780              
  Branches      165      165              
==========================================
- Hits          622      620       -2     
  Misses        102      102              
- Partials       56       58       +2     

Flag	Coverage Δ
node_10	77.02% <ø> (ø)
node_12	77.35% <ø> (ø)
node_12_15	77.35% <ø> (ø)
node_14	79.10% <ø> (-0.13%)	⬇️
node_14_13_0	78.46% <ø> (ø)
node_15	79.10% <ø> (-0.13%)	⬇️
typescript_2_7	79.10% <ø> (-0.13%)	⬇️
typescript_latest	78.46% <ø> (ø)
typescript_next	78.46% <ø> (ø)
ubuntu	79.10% <ø> (ø)
windows	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/index.ts	78.76% <0.00%> (-0.50%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d2ccc5c...442100d. Read the comment docs.

[NaridaL]

This isn't entirely unambiguous, as you could read it as both tsx and jsx are enabled if you set jsx, but I didn't really see a way of improving that short of introducing a table.

[cspotcode]

Good point; how do you feel about this wording? Too verbose? Still ambiguous?

**TypeScript Node** works by registering the TypeScript compiler for `.ts`, `.tsx`, `.js`, and `.jsx` extensions.
`.js` and `.jsx` are only registered when allowJs is true.  `.tsx` and `.jsx` are only registered when jsx is enabled.
When node.js has an extension registered (via `require.extensions`), it will use the extension internally for module resolution.
When an extension is unknown to node.js, it handles the file as `.js` (JavaScript). By default, **TypeScript Node** avoids compiling files in `/node_modules/` for three reasons:

[NaridaL]

No, that's better 👍

[NaridaL]

I changed it. I left the link in to make it obvious that jsx refers to the compiler option in this context.

[cspotcode]

Thanks, I took your lead and also added the best link I could find for allowJs. If it looks good to you, I'll go ahead and merge.

[NaridaL]

Well we both tried to quote jsx at the same time. I guess you were faster 😋

LGTG

[cspotcode]

Perfect, thank you!