pianosnake’s gists

pianosnake / width-of-degree.js

Last active August 29, 2023 15:33

Calculate the width of one degree in meters at a given latitude on Earth

	const EARTH_CIR_METERS = 40075016.686;

	function toRadians(degrees) {
	return degrees * Math.PI / 180;
	};

	function degreeWidth(lat){
	return EARTH_CIR_METERS / 360 * Math.cos(toRadians(lat));
	}

pianosnake / meters-to-pixels.js

Created June 19, 2020 19:02

Convert meters to pixels when given a map zoom level and a latitude

	const EARTH_CIR_METERS = 40075016.686;

	function toRadians(degrees) {
	return degrees * Math.PI / 180;
	};

	const metersToPixels = (meters, latitude, zoom) => {
	const metersPerPixel = EARTH_CIR_METERS / Math.pow(2, zoom + 8) * Math.cos(toRadians(latitude));
	return meters / metersPerPixel
	}

pianosnake / GoogleSheetCell.js

Last active August 8, 2019 21:54

Web component to inline a value from a Google Sheet into your HTML page. Use the component by giving it a value of the cell you'd like to display <g-cell value='a2'></g-cell> or if you need a cell from a different page of the sheet provide that number first followed by an exclamation mark <g-cell value='2!a2'></g-cell>

	// define window.sheetId sometime before loading this script. the sheet id is in the URL of the Google Sheet when you're editing it.
	if(!window.sheetId) throw Error('window.sheetId required');


	class DataProvider {
	constructor(sheetId) {
	this.sheetId = sheetId;
	this.dataPromises = {};
	}

pianosnake / most-recent-file.js

Created July 30, 2018 19:11

Get the name of the most recently created file in a given directory using Node.js

	const fs = require('fs');
	const path = require('path');

	function getMostRecentFile(dir) {
	const files = fs.readdirSync(dir);
	let earliestCreate = 0;
	let mostRecentFile = files[0];

	files.forEach(file => {
	if (fs.statSync(path.join(dir, file)).ctime > earliestCreate) {

pianosnake / bounding-box-from-lat-lng-zoom-img-size.js

Last active January 20, 2025 20:18

Get a bounding box from latitude, longitude, zoom level and image size. Useful for getting the bounding box of a static map generated with only those variables.

	const EARTH_CIR_METERS = 40075016.686;
	const degreesPerMeter = 360 / EARTH_CIR_METERS;

	function toRadians(degrees) {
	return degrees * Math.PI / 180;
	};

	function latLngToBounds(lat, lng, zoom, width, height){
	const metersPerPixelEW = EARTH_CIR_METERS / Math.pow(2, zoom + 8);
	const metersPerPixelNS = EARTH_CIR_METERS / Math.pow(2, zoom + 8) * Math.cos(toRadians(lat));

pianosnake / bounding-box-area.js

Last active July 16, 2018 22:38

Computes the area of a geographic bounding box assuming spherical Earth

	// adapted from http://mathforum.org/library/drmath/view/63767.html

	const r = 6371.0072; //earth radius in KM

	function toRadians(degrees) {
	return degrees * Math.PI / 180;
	};

	function computeArea(bbox){
	const [minLng, minLat, maxLng, maxLat] = bbox;

pianosnake / cardinalDirection.js

Last active April 18, 2018 16:00

Convert bearing (0-360 degrees) to cardinal direction (N, NW, etc...)

	//divide 360 into 16 equal slices
	const degrees = (new Array(16)).fill(null).map((x, i) => 360/16 * i + 11.25);
	const directions = ['N', 'NNE', 'NE', 'ENE', 'E', 'ESE', 'SE', 'SSE', 'S', 'SSW', 'SW', 'WSW', 'W', 'WNW', 'NW', 'NNW'];

	function cardinalDirection(bearing) {
	for (let i = 0, l = degrees.length; i < l; i++) {
	if (bearing < degrees[i]) return directions[i];
	if (i == l - 1) return directions[0];
	}
	}

pianosnake / insistent request using generators.js

Last active September 21, 2017 19:47

retry a Request repeatedly until it succeeds or the try limit is reached

	function insistentRequest(request, tryLimit){
	if(!tryLimit) return Promise.reject('tryLimit must be above 0');
	let tries = 0;

	return new Promise(function(resolve, reject){
	//create a generator object that repeatedly 'yields' the same promise until it succeeds or the try limit is reached
	const genObj = function* gen(){
	while(1){
	yield request()
	.then(resolve)

pianosnake / throttle-promises.js

Created August 22, 2017 21:13

Promise throttling using a generator

	function throttlePromises(elements, asyncForEach, groupSize){
	return new Promise(function(resolve, reject){
	//create a generator object that 'yields' for every group
	const genObj = function* gen(){
	while(elements.length > 0){
	yield Promise.all(elements.splice(0, groupSize).map(asyncForEach))
	.then(() => genObj.next());
	}
	return resolve(true);
	}();

pianosnake / gist:af8b04f9db7987f55832ca2394b74ae0

Created June 2, 2017 22:54

Find out who wrote the bad JavaScript!! Use `git blame` on each line output by ESLINT

eslint "**/**.js" -f unix | perl -n -l -e '/(.*\.js):(\d*):/ && print "$1 $2"' | xargs -n 2 sh -c 'git blame $0 -L$1,$1'