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I'm using the following JS to transform Latitude and Longitude to X and Y coordinates but now I need the contrary, transforming Latitude and Longitude to X and Y.

export const latLon2xy = (lat, lon, width, height) => {
    const x = Math.round((width * (180 + lon) / 360) % (1.5 * width))
    const rad = lat * Math.PI / 180
    const merc = 0.5 * Math.log((1 + Math.sin(rad)) / (1 - Math.sin(rad)))
    const y = Math.round((width * merc / (2 * Math.PI)))
    return {x: x, y: y}
}
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  • It seems like you're trying to reinvent the wheel here. Isn't there a javascript package with geospatial functions you could use? – csk Apr 29 '19 at 17:13
  • This answer on SO might be helpful: stackoverflow.com/a/13323592/2258 – Richard Morgan Apr 29 '19 at 18:05
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I think you will find that the proj4js library at http://proj4js.org/ does everything you need.

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  • How would I use proj4() to translate x and y from a mercator projection image to longitude and latitude? – riccardolardi May 1 '19 at 12:32
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    If you still need help after reading the fine manual and web searching I suggest you post a new question with more specifics about what you don't understand. – Jersey Andy May 2 '19 at 14:05

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