The extensibility of WordPress makes it possible for you to add new features and capabilities to your website without actually having to rebuild or change your whole theme. This is made possible by the fact that WordPress can be readily customized. Rather than starting from scratch to create a new WordPress theme, you can add functionality to your site by simply installing plugins.
There is an issue with using this strategy, even though it is simple to insert JavaSript code right into your header.php file. It can conflict with other plugins when they load their own JS scripts.
Incorporate a script into certain pages by using plugins like Headers and Footers.
You may add the script to a single page of your choosing, a specified page, or numerous pages by utilizing the functions.php file.
Adding a script from a third party to all your pages can be done by inserting the script or adding the referenced script itself in the head of your header.php template file. For example, the instantpage.js script optimizes the loading of your website. You can add instantpage.js, for example.
You may lose these modifications if you upgrade your theme. It is strongly suggested that you set up a child theme if you still want to accomplish this, even though it is highly encouraged.
In this particular instance, in which you want this script to be included everywhere, you may add the file straight to the template by following the methods that are provided below:
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