Two primary methods used to do so are defined as follows:
Method 1 – Clear JS from the Critical Rendering Path
- The async Attribute – The attribute tells the web browser to download resource right away without slowing down the HTML parsing process. After the resource is available, HTML parsing paused to successfully load the resource.
- The defer Attribute – This attribute tells the web browser to pause downloading the resource until HTML parsing is complete. Upon successful completion of the HTML parsing, the attribute tells the browser to download and render all deferred scripts. The same order is followed for downloading as the scripts appear in the document.
The primary difference between the two attributes is that defer attribute ensures order, while async doesn’t. Nonetheless, working is same in both ways.
Method 2 – Optimize Delivery of CSS Resources
- Step 1–Identify all HTML styles that are required to render above-the-fold content for a specific webpage
- Step 2–Deliver all identified styles in line with the HTML
- Step 3 – Use media attribute on the link elements that pull in the CSS files. This helps to identify CSS resources that are conditional, i.e. only required by specific devices or in distinct situations
Render blocking CSS is not impossible, but difficult to apply, especially if you don’t know how exactly it is working.