Lesson 11 — Pipeline & Nullish Coalescing

日本語

Syntax

pipe passes the left value to the right function — data flows left to right:

5 pipe double                  -- double(5)
5 pipe double pipe increment   -- increment(double(5))
data pipe transform[extra]     -- transform(data, extra)

coal returns the right side only when the left is null or undefined (JS ??). Unlike or, it keeps 0, false, and "":

config.port coal 3000          -- config.port ?? 3000
0 coal 99                      -- 0   (kept!)
0 or 99                        -- 99  (or discards falsy values)

Task

1. Pipe 5 through double, then increment — result becomes 11.

2. Use coal so port falls back to 3000 when config-port is null.

Check

npm test 11

Learn more

• Operators — Pipeline / Nullish Coalescing