Background: the preload scanner
- Slower Page Load: Due to the early download it competes for other imporact resources like the largest contentful paint element.
Important scripts: Scripts that are critical to rendering or critical to the page experience should be placed in the head of the page. For example scripts that handle your menu or your main slider or your cookie notice should be placed in the head of the page.
Less Critical Code: For scripts that do not affect page rendering or functionalities that are not required immediately upon page load, placing them in the footer can lead to better overall performance.
Best Practices and Recommendations:
Render Critical Scripts: Scripts that impact the main content of the page should be loaded render blocking in the head of the page. Try to avoid these types of scripts as they can have a huge impact on the Core Web Vitalsan pagespeed.
Critical Scripts: Scripts that are important to conversion or page interaction should be placed asynced or deferred in the head of the page
Normal Scripts: Unless they impact lay-out or require early access, place regular scripts in the footer to enhance page load speed.
Nice-to-have scripts: Scripts that you could do without if you absolutely had to should be injected once the browser is idle.
showMessage() is placed in the
<head> section of the HTML document. The function is called when the button is clicked, displaying an alert. However, this the body will not be parsed before the file 'script.js' has been loaded and executed.
showMessage() is placed at the bottom of the
<body> section, just before the closing
Example 3: Using event Listeners
I help teams pass the Core Web Vitals:
A slow website is likely to miss out on conversions and revenue. Nearly half of internet searchers don't wait three seconds for a page to load before going to another site. Ask yourself: "Is my site fast enough to convert visitors into customers?"