preloader js code example

Example 1: preload javascript

<link rel="preload" href="main.js" as="script">
  
<script src="main.js" defer></script>

Example 2: preload images javascript

let preloadedMaps = [];
    let preloadedWorkRoutes = [];
    console.log('asdasdasdas')
    function preloadImages(preloadedMaps, preloadedWorkRoutes){
      var maps = [`${workMapDesktop}`, `${workMapMobile}`, `${playMapDesktop}`, `${playMapMobile}`];
      var workRoutes = workRoutesDesktop.concat(workRoutesMobile);
      for(let i = 0; i < workRoutes.length; i++) {
        preloadedWorkRoutes[i] = new Image();
        preloadedWorkRoutes[i].src = workRoutes[i]
      }
      for(let i = 0; i < maps.length; i++) {
        preloadedMaps[i] = new Image();
        preloadedMaps[i].src = maps[i]
      }
    }        
    preloadImages(preloadedMaps, preloadedWorkRoutes);