Scripts Be in Head or Body
When it comes to the placement of scripts in an HTML document, there is no one size fits all solution. The precise use case and the trade-offs you are prepared to accept will determine this. Placing scripts in the <head> may be advantageous for crucial scripts or those with dependencies. A better user experience may result from inserting non-critical scripts or scripts that improve functionality near the end of the <body>.
The greatest results may be obtained for complicated web applications by combining these strategies with other speed optimization methods like asynchronous loading or postponed loading. Actually, the placement of scripts in an HTML document depends on the functionality and requirements of the scripts but generally, there are two common approaches for including scripts: placing them in the <head> section or the <body> section.
Placing Scripts in the <head> Section
When scripts are placed in the <head> section of the HTML document, they are loaded before the rest of the content, including the visible elements in the <body> section.
- Dependencies: If your scripts depend on other libraries or resources, including them in the <head> ensures they are loaded first, avoiding potential errors when using those scripts in the <body>.
- Performance: By placing scripts in the <head>, the browser starts downloading and parsing them earlier in the loading process.
- Render Blocking: If the scripts are large or take time to execute, they can delay the rendering of the page content in the <body>, causing a slower user experience.
- Interaction Delay: If the scripts are responsible for adding interactivity or modifying elements in the <body>, users may experience a delay in interactions if the scripts take time to load and execute.
Placing Scripts at the End of the <body>
An alternative approach is to place scripts at the end of the <body> section, just before the closing </body> tag. This is a common practice and can offer the following advantages:
- Faster Initial Rendering: Placing scripts at the end of the <body> allows the browser to render the entire page content before loading and executing the scripts.
- Reduced Render Blocking: Since scripts are loaded after the page content, they do not block the rendering of the visible elements in the <body>.
- Progressive Enhancement: In cases where JavaScript is used to enhance the page's functionality but is not critical for basic usability, placing scripts at the end of the <body> can ensure that the core content is accessible to users with JavaScript disabled.