semlinker’s gists

semlinker / big-file-without-gzip.js

Created July 31, 2022 11:49

HTTP Transfer Large Files

	const fs = require("fs");
	const http = require("http");
	const util = require("util");
	const readFile = util.promisify(fs.readFile);

	const server = http.createServer(async (req, res) => {
	res.writeHead(200, {
	"Content-Type": "text/plain;charset=utf-8",
	});
	const buffer = await readFile(__dirname + "/big-file.txt");

semlinker / util.d.ts

Created July 31, 2022 02:33

Use TypeScript Conditional Types Like a Pro

	type FunctionPropertyNames<T> = {
	[K in keyof T]: T[K] extends Function ? K : never;
	}[keyof T];
	type FunctionProperties<T> = Pick<T, FunctionPropertyNames<T>>;

	type NonFunctionPropertyNames<T> = {
	[K in keyof T]: T[K] extends Function ? never : K;
	}[keyof T];
	type NonFunctionProperties<T> = Pick<T, NonFunctionPropertyNames<T>>;

semlinker / index.html

Last active November 20, 2024 17:31

Implement Concurrent Download of Large Files in JavaScript

	<!DOCTYPE html>
	<html lang="zh-cn">
	<head>
	<meta charset="UTF-8" />
	<meta http-equiv="X-UA-Compatible" content="IE=edge" />
	<meta name="viewport" content="width=device-width, initial-scale=1.0" />
	<title>Concurrent Download Demo</title>
	<script src="multi-thread-download.js"></script>
	</head>
	<body>

semlinker / saveAs.js

Created July 25, 2022 10:46

Save File

	function saveAs({ name, buffers, mime = "application/octet-stream" }) {
	const blob = new Blob([buffers], { type: mime });
	const blobUrl = URL.createObjectURL(blob);
	const a = document.createElement("a");
	a.download = name \|\| Math.random();
	a.href = blobUrl;
	a.click();
	URL.revokeObjectURL(blob);
	}

semlinker / download-chunk.js

Created July 25, 2022 10:43

Download Chunk

	async function download({ url, chunkSize, poolLimit = 1 }) {
	const contentLength = await getContentLength(url);
	const chunks = typeof chunkSize === "number" ? Math.ceil(contentLength / chunkSize) : 1;
	const results = await asyncPool(
	poolLimit,
	[...new Array(chunks).keys()],
	(i) => {
	let start = i * chunkSize;
	let end = i + 1 == chunks ? contentLength - 1 : (i + 1) * chunkSize - 1;
	return getBinaryContent(url, start, end, i);

semlinker / get-content-length.js

Created July 25, 2022 10:34

Get content length

	function getContentLength(url) {
	return new Promise((resolve, reject) => {
	let xhr = new XMLHttpRequest();
	xhr.open("HEAD", url);
	xhr.send();
	xhr.onload = function () {
	resolve(
	~~xhr.getResponseHeader("Content-Length")
	);
	};

semlinker / concatenate.js

Created July 25, 2022 10:32

Concatenate Function

	function concatenate(arrays) {
	if (!arrays.length) return null;
	let totalLength = arrays.reduce((acc, value) => acc + value.length, 0);
	let result = new Uint8Array(totalLength);
	let length = 0;
	for (let array of arrays) {
	result.set(array, length);
	length += array.length;
	}
	return result;

semlinker / get-binary-content.js

Created July 25, 2022 10:27

Get Binary Content

	function getBinaryContent(url, start, end, i) {
	return new Promise((resolve, reject) => {
	try {
	let xhr = new XMLHttpRequest();
	xhr.open("GET", url, true);
	xhr.setRequestHeader("range", `bytes=${start}-${end}`); // Set range request information
	xhr.responseType = "arraybuffer"; // Set the returned type to arraybuffer
	xhr.onload = function () {
	resolve({
	index: i, // file block index

semlinker / promise.race.js

Created July 25, 2022 03:58

Promise.race

	Promise.race = function (iterators) {
	return new Promise((resolve, reject) => {
	for (const iter of iterators) {
	Promise.resolve(iter)
	.then((res) => {
	resolve(res);
	})
	.catch((e) => {
	reject(e);
	});

semlinker / promise.all.js

Created July 25, 2022 03:57

Promise.all

	Promise.all = function (iterators) {
	return new Promise((resolve, reject) => {
	if (!iterators \|\| iterators.length === 0) {
	resolve([]);
	} else {
	// used to determine whether all tasks are completed
	let count = 0;
	let result = []; // result array
	for (let i = 0; i < iterators.length; i++) {
	// Considering that iterators[i] may be ordinary object,

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