| /** | |
| * javascript incremental crc32 naive implementation. | |
| * based on http://www.sunshine2k.de/articles/coding/crc/understanding_crc.html#ch44 | |
| * not production ready, not efficient ! | |
| dmeo:https://replit.com/join/dzezyxlpst-jaosnhsieh | |
| * | |
| * | |
| */ |
2022.02.16 leaflet get x y z tile image on certain zoom level learn from azure-maps/zoom-levels-and-tile-grid?tabs=csharp
Each tile is given XY coordinates ranging from (0, 0) in the upper left to (2zoom–1, 2zoom–1) in the lower right. For example, at zoom level 3, the tile coordinates range from (0, 0) to (7, 7) as follows:
demo: https://jsfiddle.net/jasonHsieh/qz5yngdk/1/
for example, zoom level 2 has below urls to fetch
| var tick = 1; | |
| var maxTick = 65535; | |
| var resolution = 4; | |
| var timer; | |
| const startedAt = new Date().getTime(); | |
| module.exports = function(seconds) { | |
| var size = resolution * (seconds || 5); | |
| var buffer = [0]; |
| <!-- working example https://jsfiddle.net/qz9g53bt/2/ --> | |
| <!-- from https://github.com/allartk/leaflet.offline --> | |
| <!DOCTYPE html> | |
| <html lang="en"> | |
| <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" /> | |
| <script src="https://unpkg.com/idb@6.1.4/build/iife/index-min.js"></script> |
2022.02.09 How to find commit when line was deleted/removed?
git log -c -S'missingtext' /path/to/file
for example, i was looking for when was webpackJson got deleted in create-react-app repo
git clone https://github.com/facebook/create-react-app.git
Use zeromqjs and ruby's zeromq, sub pub pattern for ruby <-> node.js communiation.
Use zeromqjs's multiplex sockets socket("xrep") and socket("xreq") to handle RPC call.
| /* | |
| * adding extra async execuation "await wait();" actually giving setInterval some time to execute. | |
| * try comment "await wait();" | |
| */ | |
| main(); | |
| async function main() { | |
| setInterval(() => { | |
| console.log(new Date(), 'interval'); |
| // from https://forum.quasar-framework.org/topic/3375/solved-v1-download-a-file-in-cordova-app/2 | |
| window.test = {}; | |
| window.test.writeFile = (fileName, content) => { | |
| return new Promise((ok, fail) => { | |
| //@ts-ignore | |
| if (!window.requestFileSystem) { | |
| console.error(`$ window.requestFileSystem is not available`); | |
| fail(false); | |
| return; | |
| } |
| 2021.12.15 useful react hooks. previous value hook | |
| usePreviousDifferent.ts | |
| /** | |
| from: https://github.com/imbhargav5/rooks/blob/main/src/hooks/usePreviousDifferent.ts | |
| from: https://github.com/imbhargav5/rooks/blob/main/src/hooks/usePreviousDifferent.ts |
| type A = { command: 'a'; s: string }; | |
| type B = { command: 'b'; b: number }; | |
| function t(option: A | B) { | |
| switch (option.command) { | |
| case 'a': { | |
| return 's'; | |
| } | |
| case 'b': { | |
| return 1; |