How to set a preferred language for a map - Amazon Location Service
Set preferred language to Japanese and show map of JapanSet preferred language based on end user's browser language

How to set a preferred language for a map

Amazon Location Service enables you to set the preferred language at the client-side by updating the style descriptor for a specific language. You can set a preferred language and display content in that language where embedded. Otherwise, it will fall back to another language.

Note

For more information, see Localization and internationalization.

Set preferred language to Japanese and show map of Japan

In this example, you will set update style to show map labels in Japanese (ja).

index.html

    <html>
    <head>
      <link href="https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.css" rel="stylesheet" />
      <script src="https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.js"></script>
      <link href="style.css" rel="stylesheet" />
      <script src="main.js"></script>
    </head>
    <body>
      <div id="map" />
      <script>
        const apiKey = "Add Your Api Key";
        const mapStyle = "Standard";
        const awsRegion = "eu-central-1";
        const initialLocation = [139.76694, 35.68085]; //Japan   
        
        async function initializeMap() {
           // get updated style object for preferred language. 
            const styleObject = await getStyleWithPreferredLanguage("ja");
           // Initialize the MapLibre map with the fetched style object
            const map = new maplibregl.Map({
                container: 'map',
                style: styleObject,
                center: initialLocation,
                zoom: 15,
                hash:true,
            });
            map.addControl(new maplibregl.NavigationControl(), "top-left");
        
            return map; 
        }

        initializeMap();
      </script>
    </body>
    </html>
style.css

    body { margin: 0; }
    #map { height: 100vh; }
main.js

    async function getStyleWithPreferredLanguage(preferredLanguage) {
      const styleUrl = `https://maps.geo.${awsRegion}.amazonaws.com/v2/styles/${mapStyle}/descriptor?key=${apiKey}`;

      return fetch(styleUrl)
        .then(response => {
          if (!response.ok) {
            throw new Error('Network response was not ok ' + response.statusText);
          }
          return response.json();
        })
        .then(styleObject => {
          if (preferredLanguage !== "en") {
            styleObject = setPreferredLanguage(styleObject, preferredLanguage);
          }

          return styleObject;
        })
        .catch(error => {
          console.error('Error fetching style:', error);
        });
    }

    const setPreferredLanguage = (style, language) => {
      let nextStyle = { ...style };

      nextStyle.layers = nextStyle.layers.map(l => {
        if (l.type !== 'symbol' || !l?.layout?.['text-field']) return l;
        return updateLayer(l, /^name:([A-Za-z\-\_]+)$/g, `name:${language}`);
      });

      return nextStyle;
    };

    const updateLayer = (layer, prevPropertyRegex, nextProperty) => {
      const nextLayer = {
        ...layer,
        layout: {
          ...layer.layout,
          'text-field': recurseExpression(
            layer.layout['text-field'],
            prevPropertyRegex,
            nextProperty
          )
        }
      };
      return nextLayer;
    };

    const recurseExpression = (exp, prevPropertyRegex, nextProperty) => {
      if (!Array.isArray(exp)) return exp;
      if (exp[0] !== 'coalesce') return exp.map(v =>
        recurseExpression(v, prevPropertyRegex, nextProperty)
      );

      const first = exp[1];
      const second = exp[2];

      let isMatch =
      Array.isArray(first) &&
      first[0] === 'get' &&
      !!first[1].match(prevPropertyRegex)?.[0];

      isMatch = isMatch && Array.isArray(second) && second[0] === 'get';
      isMatch = isMatch && !exp?.[4];

      if (!isMatch) return exp.map(v =>
        recurseExpression(v, prevPropertyRegex, nextProperty)
      );

      return [
        'coalesce',
        ['get', nextProperty],
        ['get', 'name:en'],
        ['get', 'name']
      ];
    };

Set preferred language based on end user's browser language

In this example, you will set update style to show map labels in user's device language.

index.html

    <html>
    <head>
      <link href="https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.css" rel="stylesheet" />
      <script src="https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.js"></script>
      <link href="style.css" rel="stylesheet" />
      <script src="main.js"></script>
    </head>
    <body>
      <div id="map" />
      <script>
        const apiKey = "Add Your Api Key";
        const mapStyle = "Standard";
        const awsRegion = "eu-central-1";
        const initialLocation = [139.76694, 35.68085]; //Japan   
        const userLanguage = navigator.language || navigator.userLanguage;
        const languageCode = userLanguage.split('-')[0];

        async function initializeMap() {
           const styleObject = await getStyleWithPreferredLanguage(languageCode);
           const map = new maplibregl.Map({
                container: 'map',
                style: styleObject,
                center: initialLocation,
                zoom: 15,
                hash:true,
           });
           map.addControl(new maplibregl.NavigationControl(), "top-left");
           return map; 
        }

        initializeMap();
      </script>
    </body>
    </html>
style.css

    body { margin: 0; }
    #map { height: 100vh; }
main.js

    async function getStyleWithPreferredLanguage(preferredLanguage) {
      const styleUrl = `https://maps.geo.${awsRegion}.amazonaws.com/v2/styles/${mapStyle}/descriptor?key=${apiKey}`;

      return fetch(styleUrl)
        .then(response => {
          if (!response.ok) {
            throw new Error('Network response was not ok ' + response.statusText);
          }
          return response.json();
        })
        .then(styleObject => {
          if (preferredLanguage !== "en") {
            styleObject = setPreferredLanguage(styleObject, preferredLanguage);
          }

          return styleObject;
        })
        .catch(error => {
          console.error('Error fetching style:', error);
        });
    }

    const setPreferredLanguage = (style, language) => {
      let nextStyle = { ...style };

      nextStyle.layers = nextStyle.layers.map(l => {
        if (l.type !== 'symbol' || !l?.layout?.['text-field']) return l;
        return updateLayer(l, /^name:([A-Za-z\-\_]+)$/g, `name:${language}`);
      });

      return nextStyle;
    };

    const updateLayer = (layer, prevPropertyRegex, nextProperty) => {
      const nextLayer = {
        ...layer,
        layout: {
          ...layer.layout,
          'text-field': recurseExpression(
            layer.layout['text-field'],
            prevPropertyRegex,
            nextProperty
          )
        }
      };
      return nextLayer;
    };

    const recurseExpression = (exp, prevPropertyRegex, nextProperty) => {
      if (!Array.isArray(exp)) return exp;
      if (exp[0] !== 'coalesce') return exp.map(v =>
        recurseExpression(v, prevPropertyRegex, nextProperty)
      );

      const first = exp[1];
      const second = exp[2];

      let isMatch =
      Array.isArray(first) &&
      first[0] === 'get' &&
      !!first[1].match(prevPropertyRegex)?.[0];

      isMatch = isMatch && Array.isArray(second) && second[0] === 'get';
      isMatch = isMatch && !exp?.[4];

      if (!isMatch) return exp.map(v =>
        recurseExpression(v, prevPropertyRegex, nextProperty)
      );

      return [
        'coalesce',
        ['get', nextProperty],
        ['get', 'name:en'],
        ['get', 'name']
      ];
    };