JavaScript Variable Scope Issue in Google Maps Project

Other Questions JavaScript
1

I’m working on a Google Maps project and I’ve run into a weird problem with my search function. I’m trying to show a list of search markers on the side, matching them to different halls. But here’s the thing: my side_bar_html variable won’t show up unless I use an alert first.

Here’s a simplified version of what I’m dealing with:

let sideBarContent = '';

function searchArea(query, mapObject) {
  // ... some code to fetch and process data ...

  for (let i = 0; i < locations.length; i++) {
    let marker = createMarker(locations[i]);
    mapObject.addMarker(marker);
  }

  console.log(sideBarContent); // This is empty unless I use an alert

  let searchPanel = new UIPanel(`
    <div class='search-results'>
      <h3>Search Results</h3>
      ${sideBarContent}
    </div>
  `);
  mapObject.addPanel(searchPanel);
}

function createMarker(location) {
  let marker = new MapMarker(location.coords);
  marker.onClick(() => {
    marker.showInfo(`<a href='#'>${location.name}</a>`);
  });

  sideBarContent += `<a href='#'>${location.name}</a><br>`;
  return marker;
}

Why is sideBarContent empty when I try to use it? It only works if I add an alert before using it. I’m new to JavaScript and I’m not sure what I’m doing wrong. Any ideas?

2

I’ve encountered similar issues in my own projects. The problem likely stems from the asynchronous nature of marker creation. Here’s what worked for me:

Try using a callback function or a Promise to ensure all markers are created before updating the panel. Something like this:

function searchArea(query, mapObject) {
  let sideBarContent = '';
  let markerPromises = locations.map(location => 
    createMarker(location).then(marker => {
      mapObject.addMarker(marker);
      sideBarContent += `<a href='#'>${location.name}</a><br>`;
    })
  );

  Promise.all(markerPromises).then(() => {
    let searchPanel = new UIPanel(`
      <div class='search-results'>
        <h3>Search Results</h3>
        ${sideBarContent}
      </div>
    `);
    mapObject.addPanel(searchPanel);
  });
}

This approach ensures all markers are created and added before updating the panel. It solved my timing issues without resorting to hacky solutions like alerts or timeouts.

3

This looks like a closure issue with variable scoping. Your sideBarContent is declared outside the functions, but it’s being modified inside createMarker. Try declaring sideBarContent inside searchArea and passing it as a parameter to createMarker. This way, you ensure the variable is properly scoped and updated. Also, consider using a more descriptive name like searchResultsHtml for clarity. If the issue persists, you might need to investigate if any asynchronous operations are happening during marker creation that could delay the content update.

4

sounds like a classic timing issue mate. ur createMarker function is probably async, so sideBarContent isn’t populated when u try to use it. try using Promise.all() to wait for all markers to be created before adding the panel. or use setTimeout to delay panel creation a bit. good luck!