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Comparing layers
This example allows comparison of two layers with resizable map panes using theSplit.jslibrary.
TypeScript
functioninitMap():void{constmapOptions={center:{lat:44.5250489,lng:-110.83819},zoom:18,scaleControl:false,streetViewControl:false,};// instantiate the map on the left with control positioningmapLeft=newgoogle.maps.Map(document.getElementById("map-left")asHTMLElement,{...mapOptions,mapTypeId:"satellite",tilt:0,// at high zoom levels we need to maintain the same projectionfullscreenControlOptions:{position:google.maps.ControlPosition.LEFT_BOTTOM,},mapTypeControlOptions:{position:google.maps.ControlPosition.LEFT_TOP,},zoomControlOptions:{position:google.maps.ControlPosition.LEFT_BOTTOM,},});// instantiate the map on the right with control positioningmapRight=newgoogle.maps.Map(document.getElementById("map-right")asHTMLElement,{...mapOptions,fullscreenControlOptions:{position:google.maps.ControlPosition.RIGHT_BOTTOM,},mapTypeControlOptions:{position:google.maps.ControlPosition.RIGHT_TOP,},zoomControlOptions:{position:google.maps.ControlPosition.RIGHT_BOTTOM,},});// helper function to keep maps in syncfunctionsync(...maps:google.maps.Map[]){letcenter:google.maps.LatLng,zoom:number;functionupdate(changedMap){maps.forEach((m)=>{if(m===changedMap){return;}m.setCenter(center);m.setZoom(zoom);});}maps.forEach((m)=>{m.addListener("bounds_changed",()=>{constchangedCenter=m.getCenter()!;constchangedZoom=m.getZoom()!;if(changedCenter!==center||changedZoom!==zoom){center=changedCenter;zoom=changedZoom;update(m);}});});}sync(mapLeft,mapRight);functionhandleContainerResize(){constwidth=(document.getElementById("container")asHTMLElement).offsetWidth;(document.getElementById("map-left")asHTMLElement).style.width=`${width}px`;(document.getElementById("map-right")asHTMLElement).style.width=`${width}px`;}// trigger to set map container size since using absolutehandleContainerResize();// add event listenerwindow.addEventListener("resize",handleContainerResize);//@ts-ignoreSplit(["#left","#right"],{sizes:[50,50],});}declareglobal{interfaceWindow{initMap:()=>void;}}window.initMap=initMap;
functioninitMap(){constmapOptions={center:{lat:44.5250489,lng:-110.83819},zoom:18,scaleControl:false,streetViewControl:false,};// instantiate the map on the left with control positioningmapLeft=newgoogle.maps.Map(document.getElementById("map-left"),{...mapOptions,mapTypeId:"satellite",tilt:0,// at high zoom levels we need to maintain the same projectionfullscreenControlOptions:{position:google.maps.ControlPosition.LEFT_BOTTOM,},mapTypeControlOptions:{position:google.maps.ControlPosition.LEFT_TOP,},zoomControlOptions:{position:google.maps.ControlPosition.LEFT_BOTTOM,},});// instantiate the map on the right with control positioningmapRight=newgoogle.maps.Map(document.getElementById("map-right"),{...mapOptions,fullscreenControlOptions:{position:google.maps.ControlPosition.RIGHT_BOTTOM,},mapTypeControlOptions:{position:google.maps.ControlPosition.RIGHT_TOP,},zoomControlOptions:{position:google.maps.ControlPosition.RIGHT_BOTTOM,},});// helper function to keep maps in syncfunctionsync(...maps){letcenter,zoom;functionupdate(changedMap){maps.forEach((m)=>{if(m===changedMap){return;}m.setCenter(center);m.setZoom(zoom);});}maps.forEach((m)=>{m.addListener("bounds_changed",()=>{constchangedCenter=m.getCenter();constchangedZoom=m.getZoom();if(changedCenter!==center||changedZoom!==zoom){center=changedCenter;zoom=changedZoom;update(m);}});});}sync(mapLeft,mapRight);functionhandleContainerResize(){constwidth=document.getElementById("container").offsetWidth;document.getElementById("map-left").style.width=`${width}px`;document.getElementById("map-right").style.width=`${width}px`;}// trigger to set map container size since using absolutehandleContainerResize();// add event listenerwindow.addEventListener("resize",handleContainerResize);//@ts-ignoreSplit(["#left","#right"],{sizes:[50,50],});}window.initMap=initMap;
/** Always set the map height explicitly to define the size of the div element* that contains the map.*/#map{height:100%;}/** Optional: Makes the sample page fill the window.*/html,body{height:100%;margin:0;padding:0;}#container,#left,#right,.map,.gutter{height:100%;}#left,#right,.gutter{float:left;position:relative;overflow:hidden;}#map-left{position:absolute;left:0;top:0;}#map-right{position:absolute;right:0;top:0;}.gutter{background-color:#eee;background-repeat:no-repeat;background-position:50%;}.gutter.gutter-horizontal{cursor:col-resize;background-image:url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg==");}
<html>
<head>
<title>Split Map Panes</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js"></script>
<link rel="stylesheet" type="text/css" href="./style.css" />
<script type="module" src="./index.js"></script>
</head>
<body>
<div id="container">
<div id="left">
<div id="map-left" class="map"></div>
</div>
<div id="right">
<div id="map-right" class="map"></div>
</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&v=weekly"
defer
></script>
</body>
</html>
Git and Node.js are required to run this sample locally. Follow theseinstructionsto install Node.js and NPM. The following commands clone, install dependencies and start the sample application.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis example demonstrates how to compare two Google Maps layers side-by-side using resizable panes.\u003c/p\u003e\n"],["\u003cp\u003eIt utilizes the Split.js library to create and manage the resizable panes for a seamless user experience.\u003c/p\u003e\n"],["\u003cp\u003eThe code synchronizes the two map instances, ensuring that they maintain the same center and zoom level as the user interacts with either pane.\u003c/p\u003e\n"],["\u003cp\u003eBoth TypeScript and JavaScript code snippets are provided, along with HTML and CSS for styling and structure.\u003c/p\u003e\n"],["\u003cp\u003eUsers can clone and run the sample locally using Git and Node.js or try it directly in Google Cloud Shell.\u003c/p\u003e\n"]]],["This code demonstrates comparing two map layers using resizable panes. It initializes two Google Maps instances (`mapLeft`, `mapRight`) with synchronized center and zoom. The `sync` function ensures both maps stay aligned during navigation. `handleContainerResize` sets map container sizes, and a `resize` event listener is added. The Split.js library is used to make the map panes resizable, with the panes set to an initial 50/50 split.\n"],null,["# Resizable Split Map Panes\n\nComparing layers\n----------------\n\nThis example allows comparison of two layers with resizable map panes using the\n[Split.js](https://github.com/nathancahill/split/tree/master/packages/splitjs)\nlibrary. \n\n### TypeScript\n\n```typescript\nfunction initMap(): void {\n const mapOptions = {\n center: { lat: 44.5250489, lng: -110.83819 },\n zoom: 18,\n scaleControl: false,\n streetViewControl: false,\n };\n\n // instantiate the map on the left with control positioning\n mapLeft = new google.maps.Map(\n document.getElementById(\"map-left\") as HTMLElement,\n {\n ...mapOptions,\n mapTypeId: \"satellite\",\n tilt: 0, // at high zoom levels we need to maintain the same projection\n fullscreenControlOptions: {\n position: google.maps.ControlPosition.LEFT_BOTTOM,\n },\n mapTypeControlOptions: {\n position: google.maps.ControlPosition.LEFT_TOP,\n },\n zoomControlOptions: {\n position: google.maps.ControlPosition.LEFT_BOTTOM,\n },\n }\n );\n\n // instantiate the map on the right with control positioning\n mapRight = new google.maps.Map(\n document.getElementById(\"map-right\") as HTMLElement,\n {\n ...mapOptions,\n fullscreenControlOptions: {\n position: google.maps.ControlPosition.RIGHT_BOTTOM,\n },\n mapTypeControlOptions: {\n position: google.maps.ControlPosition.RIGHT_TOP,\n },\n zoomControlOptions: {\n position: google.maps.ControlPosition.RIGHT_BOTTOM,\n },\n }\n );\n\n // helper function to keep maps in sync\n function sync(...maps: google.maps.Map[]) {\n let center: google.maps.LatLng, zoom: number;\n\n function update(changedMap) {\n maps.forEach((m) =\u003e {\n if (m === changedMap) {\n return;\n }\n\n m.setCenter(center);\n m.setZoom(zoom);\n });\n }\n\n maps.forEach((m) =\u003e {\n m.addListener(\"bounds_changed\", () =\u003e {\n const changedCenter = m.getCenter()!;\n const changedZoom = m.getZoom()!;\n\n if (changedCenter !== center || changedZoom !== zoom) {\n center = changedCenter;\n zoom = changedZoom;\n update(m);\n }\n });\n });\n }\n\n sync(mapLeft, mapRight);\n\n function handleContainerResize() {\n const width = (document.getElementById(\"container\") as HTMLElement)\n .offsetWidth;\n\n (\n document.getElementById(\"map-left\") as HTMLElement\n ).style.width = `${width}px`;\n (\n document.getElementById(\"map-right\") as HTMLElement\n ).style.width = `${width}px`;\n }\n\n // trigger to set map container size since using absolute\n handleContainerResize();\n // add event listener\n window.addEventListener(\"resize\", handleContainerResize);\n\n //@ts-ignore\n Split([\"#left\", \"#right\"], {\n sizes: [50, 50],\n });\n}\n\ndeclare global {\n interface Window {\n initMap: () =\u003e void;\n }\n}\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/samples/split-map-panes/index.ts#L9-L112\n```\n| **Note:** Read the [guide](/maps/documentation/javascript/using-typescript) on using TypeScript and Google Maps.\n\n### JavaScript\n\n```javascript\nfunction initMap() {\n const mapOptions = {\n center: { lat: 44.5250489, lng: -110.83819 },\n zoom: 18,\n scaleControl: false,\n streetViewControl: false,\n };\n\n // instantiate the map on the left with control positioning\n mapLeft = new google.maps.Map(document.getElementById(\"map-left\"), {\n ...mapOptions,\n mapTypeId: \"satellite\",\n tilt: 0, // at high zoom levels we need to maintain the same projection\n fullscreenControlOptions: {\n position: google.maps.ControlPosition.LEFT_BOTTOM,\n },\n mapTypeControlOptions: {\n position: google.maps.ControlPosition.LEFT_TOP,\n },\n zoomControlOptions: {\n position: google.maps.ControlPosition.LEFT_BOTTOM,\n },\n });\n // instantiate the map on the right with control positioning\n mapRight = new google.maps.Map(document.getElementById(\"map-right\"), {\n ...mapOptions,\n fullscreenControlOptions: {\n position: google.maps.ControlPosition.RIGHT_BOTTOM,\n },\n mapTypeControlOptions: {\n position: google.maps.ControlPosition.RIGHT_TOP,\n },\n zoomControlOptions: {\n position: google.maps.ControlPosition.RIGHT_BOTTOM,\n },\n });\n\n // helper function to keep maps in sync\n function sync(...maps) {\n let center, zoom;\n\n function update(changedMap) {\n maps.forEach((m) =\u003e {\n if (m === changedMap) {\n return;\n }\n\n m.setCenter(center);\n m.setZoom(zoom);\n });\n }\n\n maps.forEach((m) =\u003e {\n m.addListener(\"bounds_changed\", () =\u003e {\n const changedCenter = m.getCenter();\n const changedZoom = m.getZoom();\n\n if (changedCenter !== center || changedZoom !== zoom) {\n center = changedCenter;\n zoom = changedZoom;\n update(m);\n }\n });\n });\n }\n\n sync(mapLeft, mapRight);\n\n function handleContainerResize() {\n const width = document.getElementById(\"container\").offsetWidth;\n\n document.getElementById(\"map-left\").style.width = `${width}px`;\n document.getElementById(\"map-right\").style.width = `${width}px`;\n }\n\n // trigger to set map container size since using absolute\n handleContainerResize();\n // add event listener\n window.addEventListener(\"resize\", handleContainerResize);\n //@ts-ignore\n Split([\"#left\", \"#right\"], {\n sizes: [50, 50],\n });\n}\n\nwindow.initMap = initMap;https://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/split-map-panes/docs/index.js#L9-L94\n```\n| **Note:** The JavaScript is compiled from the TypeScript snippet.\n\n### CSS\n\n```css\n/* \n * Always set the map height explicitly to define the size of the div element\n * that contains the map. \n */\n#map {\n height: 100%;\n}\n\n/* \n * Optional: Makes the sample page fill the window. \n */\nhtml,\nbody {\n height: 100%;\n margin: 0;\n padding: 0;\n}\n\n#container,\n#left,\n#right,\n.map,\n.gutter {\n height: 100%;\n}\n\n#left,\n#right,\n.gutter {\n float: left;\n position: relative;\n overflow: hidden;\n}\n\n#map-left {\n position: absolute;\n left: 0;\n top: 0;\n}\n\n#map-right {\n position: absolute;\n right: 0;\n top: 0;\n}\n\n.gutter {\n background-color: #eee;\n background-repeat: no-repeat;\n background-position: 50%;\n}\n\n.gutter.gutter-horizontal {\n cursor: col-resize;\n background-image: url(\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg==\");\n}\nhttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/split-map-panes/docs/style.css#L7-L63\n```\n\n### HTML\n\n```html\n\u003chtml\u003e\n \u003chead\u003e\n \u003ctitle\u003eSplit Map Panes\u003c/title\u003e\n\n \u003cscript src=\"https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js\"\u003e\u003c/script\u003e\n\n \u003clink rel=\"stylesheet\" type=\"text/css\" href=\"./style.css\" /\u003e\n \u003cscript type=\"module\" src=\"./index.js\"\u003e\u003c/script\u003e\n \u003c/head\u003e\n \u003cbody\u003e\n \u003cdiv id=\"container\"\u003e\n \u003cdiv id=\"left\"\u003e\n \u003cdiv id=\"map-left\" class=\"map\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"right\"\u003e\n \u003cdiv id=\"map-right\" class=\"map\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\n \u003c!-- \n The `defer` attribute causes the script to execute after the full HTML\n document has been parsed. For non-blocking uses, avoiding race conditions,\n and consistent behavior across browsers, consider loading using Promises. See\n https://developers.google.com/maps/documentation/javascript/load-maps-js-api\n for more information.\n --\u003e\n \u003cscript\n src=\"https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly\"\n defer\n \u003e\u003c/script\u003e\n \u003c/body\u003e\n\u003c/html\u003ehttps://github.com/googlemaps/js-samples/blob/2683f7366fb27829401945d2a7e27d77ed2df8e5/dist/samples/split-map-panes/docs/index.html#L8-L39\n```\n\n### Try Sample\n\n[Google Cloud Shell](https://ssh.cloud.google.com/cloudshell/editor?cloudshell_git_repo=https%3A%2F%2Fgithub.com%2Fgooglemaps%2Fjs-samples&cloudshell_git_branch=sample-split-map-panes&cloudshell_tutorial=cloud_shell_instructions.md&cloudshell_workspace=.)\n\n### Clone Sample\n\n\nGit and Node.js are required to run this sample locally. Follow these [instructions](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm) to install Node.js and NPM. The following commands clone, install dependencies and start the sample application. \n\n git clone -b sample-split-map-panes https://github.com/googlemaps/js-samples.git\n cd js-samples\n npm i\n npm start\n\n\nOther samples can be tried by switching to any branch beginning with `sample-`\u003cvar translate=\"no\"\u003eSAMPLE_NAME\u003c/var\u003e. \n\n git checkout sample-\u003cvar translate=\"no\"\u003e\u003cspan class=\"devsite-syntax-nx\"\u003eSAMPLE_NAME\u003c/span\u003e\u003c/var\u003e\n npm i\n npm start"]]
