waitOnResources.md

April 22, 2026 ยท View on GitHub

waitOnResources hook

waitOnResources(params, queryParams)

  • params {Object} - Serialized route parameters, /route/:_id => { _id: 'str' }
  • queryParams {Object} - Query params object, /route/?key=val => { key: 'val' }
  • Return: {Object} { images: ['url'], other: ['url'] }

.waitOnResources() hook is triggered before .action() hook, allowing to load necessary files, images, fonts before rendering a template.

Preload images

FlowRouter.route('/images', {
  name: 'images',
  waitOnResources() {
    return {
      images:[
        '/imgs/1.png',
        '/imgs/2.png',
        '/imgs/3.png'
      ]
    };
  },
});

Global images preload

Useful to preload background images and other globally used resources

FlowRouter.globals.push({
  waitOnResources() {
    return {
      images: [
        '/imgs/background/jpg',
        '/imgs/icon-sprite.png',
        '/img/logo.png'
      ]
    };
  }
});

Preload Resources

This method will work only for cacheable resources, if URLs returns non-cacheable resources (dynamic resources) it will be useless.

Tip

Why Images and Other resources are separated? What the difference?

  • Images can be prefetched via Image() constructor, all other resources will use XMLHttpRequest or fetch() to cache resources. That's why important to make sure requested URLs returns cacheable response.
FlowRouter.route('/', {
  name: 'index',
  waitOnResources() {
    return {
      other:[
        '/fonts/OpenSans-Regular.eot',
        '/fonts/OpenSans-Regular.svg',
        '/fonts/OpenSans-Regular.ttf',
        '/fonts/OpenSans-Regular.woff',
        '/fonts/OpenSans-Regular.woff2'
      ]
    };
  }
});

Global resources preload

Useful to prefetch Fonts and other globally used resources

FlowRouter.globals.push({
  waitOnResources() {
    return {
      other:[
        '/fonts/OpenSans-Regular.eot',
        '/fonts/OpenSans-Regular.svg',
        '/fonts/OpenSans-Regular.ttf',
        '/fonts/OpenSans-Regular.woff',
        '/fonts/OpenSans-Regular.woff2'
      ]
    };
  }
});

Further reading