@types/proj4

Coordinate Transformation

This feature allows you to transform coordinates from one projection system to another. In this example, coordinates in EPSG:4326 (WGS 84) are transformed to EPSG:3857 (Web Mercator).

const proj4 = require('proj4');
const firstProjection = 'EPSG:4326';
const secondProjection = 'EPSG:3857';
const coordinates = [2.2945, 48.8584];
const transformedCoordinates = proj4(firstProjection, secondProjection, coordinates);
console.log(transformedCoordinates);

Defining Custom Projections

This feature allows you to define custom projections. In this example, a custom UTM projection is defined and then used to transform coordinates to EPSG:4326.

const proj4 = require('proj4');
const customProjection = '+proj=utm +zone=33 +ellps=WGS84 +datum=WGS84 +units=m +no_defs';
proj4.defs('EPSG:32633', customProjection);
const coordinates = [500000, 4649776.22482];
const transformedCoordinates = proj4('EPSG:32633', 'EPSG:4326', coordinates);
console.log(transformedCoordinates);

Batch Transformations

This feature allows you to perform batch transformations on an array of coordinates. In this example, an array of coordinates in EPSG:4326 is transformed to EPSG:3857.

const proj4 = require('proj4');
const firstProjection = 'EPSG:4326';
const secondProjection = 'EPSG:3857';
const coordinatesArray = [[2.2945, 48.8584], [13.4050, 52.5200]];
const transformedCoordinatesArray = coordinatesArray.map(coords => proj4(firstProjection, secondProjection, coords));
console.log(transformedCoordinatesArray);