Crude TS equivalent of Unix command-line utility.
Illustrates multiple TS features including modules and asynchronicity which were not covered in the TypeScript Overview.
To keep simple, code duplication, no real error architecture.
Command-line server-side program: fully synchronous.
Browser based program: illustrates asynchronous code.
Function jgrep(regex, content) is core of program and
used by both server-side and browser programs.
jgrep() function is pure: it has no side-effects and its
return value depends solely on its parameters.
In directory code/grep; truncation of long lines indicated by ....
$ ./dist/main.js
usage: main.js REGEX FILE...
$ ./main.mjs '[a' main.mjs
bad regex "[a"
$ ./dist/main.js '[a' src/main.ts
bad regex '[a'
$ ./dist/main.js 'for' src/Main.ts
cannot read src/Main.ts: Error: ENOENT: no such ...
$ ./dist/main.js 'for' src/main.ts
src/main.ts:27:2: for (const path of paths) {
src/main.ts:36:17: coordMatches.forEach(({lineIndex, ...
src/main.ts:37:14: matches.forEach(([colN, _]) => {
Truncation of long lines indicated by ....
$ ./dist/main.js "\(\'" src/main.ts
src/main.ts:21:9: abort('usage: %s REGEX FILE...',
$ ./dist/main.js '\$\{.+\}\`' src/main.ts
src/main.ts:38:21: console.log(`${path}:...
src/main.ts:43:31: console.error(`cannot read ${path}:...
#! shebang line is a Unix feature which allows
script execution.
The portion of the line after the #! is the absolute path for an
interpreter which the kernel sets up to run with the script file
passed in as input to the interpreter.
Use /usr/bin/env as interpreter, so that it can find nodejs
which may be in a non-standard location.
When nodejs starts up, it reads file as program to be interpreted.
Normally a # character would cause an error in a nodejs file.
nodejs ignores it only when it is on the first line of a file.
@argv: process.argv contains command-line args: argv[0]: path to
nodejs executable, argv[1]: path to script. "Real " script args
start at argv[2].
Illustrates the use of async and await for fetching
remote content.
Shows the use of anonymous functions for event handlers.
index.ts startup script.