Javascript anatomy: Difference between revisions
From wikinotes
| Line 4: | Line 4: | ||
= NodeJS CLI = | = NodeJS CLI = | ||
<blockquote> | <blockquote> | ||
{{ expand | |||
| ${PROJECT}/main.mjs | |||
| | |||
<syntaxhighlight lang="javascript"> | |||
#!/usr/bin/env node | |||
import * as Process from 'node:process' | |||
import * as Path from 'node:path' | |||
const EXECUTABLE = Path.basename(Process.argv[1]); | |||
class CliCommand { | |||
help = false; | |||
verbose = false; | |||
static fromArgs() { | |||
var cmd = new CliCommand(); | |||
var argv = Process.argv.slice(2); | |||
while (argv.length) { | |||
var item = argv.shift(); | |||
switch (item) { | |||
case "-h": case "--help": | |||
cmd.help = true; | |||
break; | |||
case "-v": case "--verbose": | |||
cmd.verbose = true; | |||
break; | |||
default: | |||
console.error(`Invalid Param: '${item}'. See --help`); | |||
Process.exit(1); | |||
} | |||
} | |||
return cmd; | |||
} | |||
exec() { | |||
if (this.help) { | |||
showHelp(); | |||
Process.exit(0); | |||
} | |||
if (this.verbose) { | |||
console.debug("loggers set to stun"); | |||
} | |||
console.log(".. your program starts here"); | |||
} | |||
} | |||
function showHelp() { | |||
var msg = `${EXECUTABLE} [-h] [-v] | |||
ARGS: | |||
-h --help | |||
show this help message. | |||
EXAMPLE: | |||
${EXECUTABLE} -h # show help | |||
`.trim() | |||
console.log(msg); | |||
} | |||
function main() { | |||
var cmd = CliCommand.fromArgs(); | |||
cmd.exec(); | |||
} | |||
main(); | |||
</syntaxhighlight> | |||
}} | |||
<syntaxhighlight lang="bash"> | |||
./main.mjs -h # run | |||
</syntaxhighlight> | |||
</blockquote><!-- NodeJS Cli --> | </blockquote><!-- NodeJS Cli --> | ||
Revision as of 22:10, 18 December 2022
NodeJS CLI
${PROJECT}/main.mjs
#!/usr/bin/env node import * as Process from 'node:process' import * as Path from 'node:path' const EXECUTABLE = Path.basename(Process.argv[1]); class CliCommand { help = false; verbose = false; static fromArgs() { var cmd = new CliCommand(); var argv = Process.argv.slice(2); while (argv.length) { var item = argv.shift(); switch (item) { case "-h": case "--help": cmd.help = true; break; case "-v": case "--verbose": cmd.verbose = true; break; default: console.error(`Invalid Param: '${item}'. See --help`); Process.exit(1); } } return cmd; } exec() { if (this.help) { showHelp(); Process.exit(0); } if (this.verbose) { console.debug("loggers set to stun"); } console.log(".. your program starts here"); } } function showHelp() { var msg = `${EXECUTABLE} [-h] [-v] ARGS: -h --help show this help message. EXAMPLE: ${EXECUTABLE} -h # show help `.trim() console.log(msg); } function main() { var cmd = CliCommand.fromArgs(); cmd.exec(); } main();./main.mjs -h # run
Web Browser
Some features of javascript (ex. ES6 modules) do not work when loading webpages directly from the filesystem.
You can use a tiny toy web-server like python http or golang simple-go-web-server to load your javascript instead.${PROJECT}/index.html
<!doctype html public "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd"> <html lang="en"> <head> <title>My Website</title> <script type="module" src="main.js"></script> <!-- <link rel="stylesheet" href="stylesheet.css" /> --> </head> <body> <h1>My Title</h1> <p>Some paragraph</p> <div id="sum-div"> <button id="sum-btn">Add</button> <input class="addend" type="text" placeholder="1"> <input class="addend" type="text" placeholder="2"> <span>=</span> <input class="result" type="text" readonly="1"> </div> </body> </html>${PROJECT}/main.js
import * as Math from './modules/math.js' function sumClicked() { var sum_btn = document.getElementById("sum-div"); var addend_inputs = Array.from(sum_btn.querySelectorAll(".addend")); var addend_values = addend_inputs.map((input) => { return Number(input.value) }); var sum = Math.sum(...addend_values); var result_input = sum_btn.querySelector(".result"); result_input.setAttribute("value", String(sum)); } document.getElementById("sum-btn").addEventListener("click", sumClicked);${PROJECT}/modules/math.js
export function sum(a, b) { return a + b; } export function multiply(a, b) { return a * b; }
open 'http://localhost:3000' simple-go-web-server --hot # reload to get changes
