DNS prefetching and preconnecting are hints of browser Banner Design resources that can be used to speed up DNS lookups. Browsers usually wait until they need a resource before trying to query the origin of that resource. While this resource is requested, the entire page load is suspended until it is resolved. DNS prefetching is a way to call the origin of non-critical resources before they are needed, which speeds up lookup time by giving the browser a head start. You Banner Design can pre-fetch third-party widgets that will be displayed at the bottom of the page like chat boxes, social sharing buttons, survey widgets, etc. Chrome Developer Tools JavaScript Console Window Preconnect is also used to establish an early connection, but should be used for resources critical to page load, such as assets hosted on content delivery networks, web fonts, etc.
Advertising Continue reading below 3. Use a single Banner Design JQuery library when possible Some third-party scripts come with a jQuery library. Simply put, jQuery is a JavaScript library that simplifies the use of JavaScript functionality. Most modern websites have some Banner Design form of JavaScript, so a version of jQuery is already loaded on the site. It's a waste of resources to pull two versions of this library to your site when you only need one. When loading an external script, always ask for a version that does not load its version of jQuery. Your developer can then set the script to use the global version being loaded on your site. Don't forget to test that the script you upload is Banner Design compatible with your site's version of jQuery.
Use the Chrome Developer Tools JavaScript Console window Banner Design to see the version(s) of jQuery currently loaded on your site. Type Ctrl+Shift+J to open the console, then type console.log(jQuery().jquery); in the command line. Chrome Developer Tools JavaScript Console Window Yellow Lab Tools has a simple interface for checking jQuery versions. jQuery Yellow Lab Tools Result Other ways to reduce the impact of uploading jQuery files include Banner Design using the latest version and distributing jQuery through Google's hosted libraries. Advertising Continue reading below 4. Remove Redundant CSS Instructions for Old Browser Support The older the site, the higher the number of violations. Removing redundant CSS instructions such as old browser support (IE patches) and old prefixes is easy because it's usually a separate block of code.