This example adds a predefined symbol (an arrow) to a polyline.

Read the [documentation](https://developers.google.com/maps/documentation/javascript/symbols.md.txt).
<iframe src="https://geo-devrel-javascript-samples.web.app/samples/overlay-symbol-arrow/app/dist/" allow="fullscreen; "></iframe>

### TypeScript

```typescript
// This example adds a predefined symbol (an arrow) to a polyline.
// Setting offset to 100% places the arrow at the end of the line.

function initMap(): void {
  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      zoom: 6,
      center: { lat: 20.291, lng: 153.027 },
      mapTypeId: "terrain",
    }
  );

  // Define a symbol using a predefined path (an arrow)
  // supplied by the Google Maps JavaScript API.
  const lineSymbol = {
    path: google.maps.SymbolPath.FORWARD_CLOSED_ARROW,
  };

  // Create the polyline and add the symbol via the 'icons' property.
  const line = new google.maps.Polyline({
    path: [
      { lat: 22.291, lng: 153.027 },
      { lat: 18.291, lng: 153.027 },
    ],
    icons: [
      {
        icon: lineSymbol,
        offset: "100%",
      },
    ],
    map: map,
  });
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;
```

> [!NOTE]
> **Note:** Read the [guide](https://developers.google.com/maps/documentation/javascript/using-typescript.md.txt) on using TypeScript and Google Maps.

### JavaScript

```javascript
// This example adds a predefined symbol (an arrow) to a polyline.
// Setting offset to 100% places the arrow at the end of the line.
function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    zoom: 6,
    center: { lat: 20.291, lng: 153.027 },
    mapTypeId: "terrain",
  });
  // Define a symbol using a predefined path (an arrow)
  // supplied by the Google Maps JavaScript API.
  const lineSymbol = {
    path: google.maps.SymbolPath.FORWARD_CLOSED_ARROW,
  };
  // Create the polyline and add the symbol via the 'icons' property.
  const line = new google.maps.Polyline({
    path: [
      { lat: 22.291, lng: 153.027 },
      { lat: 18.291, lng: 153.027 },
    ],
    icons: [
      {
        icon: lineSymbol,
        offset: "100%",
      },
    ],
    map: map,
  });
}

window.initMap = initMap;
```

> [!NOTE]
> **Note:** The JavaScript is compiled from the TypeScript snippet.

### CSS

```css
/* 
 * 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;
}
```

### HTML

```html
<html>
  <head>
    <title>Arrow Symbols (Polyline)</title>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></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>
```

### Clone Sample


Git 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.

```javascript
  git clone -b sample-overlay-symbol-arrow https://github.com/googlemaps/js-samples.git
  cd js-samples
  npm i
  npm start
```


Other samples can be tried by switching to any branch beginning with `sample-SAMPLE_NAME`.

```javascript
  git checkout sample-SAMPLE_NAME
  npm i
  npm start
```