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Encoding Methods

  • This example shows how to encode a polyline path using the Google Maps Geometry library.

  • Users can click on the map to create a polyline, and the encoded path will be displayed.

  • The encoded path is a compact representation of the polyline's coordinates.

  • Code samples are provided in TypeScript and JavaScript, alongside CSS and HTML for a complete implementation.

This example demonstrates path encoding using the Geometry library. Click themap to create a polyline. The encoding of this polyline then appears in the textbox.

Read thedocumentation.

TypeScript

// This example requires the Geometry library. Include the libraries=geometry// parameter when you first load the API. For example:// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry">functioninitMap():void{constmap=newgoogle.maps.Map(document.getElementById("map")asHTMLElement,{zoom:14,center:{lat:34.366,lng:-89.519},});constpoly=newgoogle.maps.Polyline({strokeColor:"#000000",strokeOpacity:1,strokeWeight:3,map:map,});// Add a listener for the click eventgoogle.maps.event.addListener(map,"click",(event)=>{addLatLngToPoly(event.latLng,poly);});}/** * Handles click events on a map, and adds a new point to the Polyline. * Updates the encoding text area with the path's encoded values. */functionaddLatLngToPoly(latLng:google.maps.LatLng,poly:google.maps.Polyline){constpath=poly.getPath();// Because path is an MVCArray, we can simply append a new coordinate// and it will automatically appearpath.push(latLng);// Update the text field to display the polyline encodingsconstencodeString=google.maps.geometry.encoding.encodePath(path);if(encodeString){(document.getElementById("encoded-polyline")asHTMLInputElement).value=encodeString;}}declareglobal{interfaceWindow{initMap:()=>void;}}window.initMap=initMap;
Note: Read theguide on using TypeScript and Google Maps.

JavaScript

// This example requires the Geometry library. Include the libraries=geometry// parameter when you first load the API. For example:// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry">functioninitMap(){constmap=newgoogle.maps.Map(document.getElementById("map"),{zoom:14,center:{lat:34.366,lng:-89.519},});constpoly=newgoogle.maps.Polyline({strokeColor:"#000000",strokeOpacity:1,strokeWeight:3,map:map,});// Add a listener for the click eventgoogle.maps.event.addListener(map,"click",(event)=>{addLatLngToPoly(event.latLng,poly);});}/** * Handles click events on a map, and adds a new point to the Polyline. * Updates the encoding text area with the path's encoded values. */functionaddLatLngToPoly(latLng,poly){constpath=poly.getPath();// Because path is an MVCArray, we can simply append a new coordinate// and it will automatically appearpath.push(latLng);// Update the text field to display the polyline encodingsconstencodeString=google.maps.geometry.encoding.encodePath(path);if(encodeString){document.getElementById("encoded-polyline").value=encodeString;}}window.initMap=initMap;
Note: The JavaScript is compiled from the TypeScript snippet.

CSS

/* Optional: Makes the sample page fill the window. */html,body{height:100%;margin:0;padding:0;}#container{height:100%;display:flex;}#sidebar{flex-basis:15rem;flex-grow:1;padding:1rem;max-width:30rem;height:100%;box-sizing:border-box;overflow:auto;}#map{flex-basis:0;flex-grow:4;height:100%;}#encoded-polyline{height:100px;width:100%;}

HTML

<html>  <head>    <title>Encoding Methods</title>    <link rel="stylesheet" type="text/css" href="./style.css" />    <script type="module" src="./index.js"></script>  </head>  <body>    <div>      <div></div>      <div>        <div>Encoding:</div>        <textarea></textarea>      </div>    </div>    <!--       The `defer` attribute causes the script to execute after the full HTML      document has been parsed. For non-blocking uses, avoiding race conditions,      and consistent behavior across browsers, consider loading using Promises. See      https://developers.google.com/maps/documentation/javascript/load-maps-js-api      for more information.      -->    <script      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&libraries=geometry&v=weekly"      defer    ></script>  </body></html>

Try Sample

Clone Sample

Git and Node.js are required to run this sample locally. Follow theseinstructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.

gitclone-bsample-geometry-encodingshttps://github.com/googlemaps/js-samples.gitcdjs-samplesnpminpmstart

Other samples can be tried by switching to any branch beginning withsample-SAMPLE_NAME.

gitcheckoutsample-SAMPLE_NAMEnpminpmstart

Except as otherwise noted, the content of this page is licensed under theCreative Commons Attribution 4.0 License, and code samples are licensed under theApache 2.0 License. For details, see theGoogle Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-11-21 UTC.