How Custom Pages Are Made
This is a narrative about how PHP and JavaScript are used to generate and update a custom web page. There is no code here, just a concept of how it is done.
-
PHP is used to create the web page before the page is sent to the browser.
-
JavaScript is used to update the web page after the browser receives the page.
Let's unpack.
1. PHP used to create the web page:
PHP has access to files and SQL databases on the server. JavaScript does not. Therefore, it is PHP's job to customize the web page whenever the customization is affected by anything residing in a server file or SQL database.
PHP code is in the file that contains the source code of the web page. But, when it gets to the browser, no PHP code is present.
In other words, when you use your browser's "view source" menu item, the source code it presents will have no PHP code in it — even though the original web page file on the server has PHP code.
2. JavaScript used to update the web page:
When the web page has been delivered to the browser, it is up to JavaScript to do any modifications. PHP can no longer reach it.
If the JavaScript needs information from a server file or SQL database on the server, it can not get the information by itself. The JavaScript needs to get in touch with a web page or script on the server that fetches the information and returns it.
Generally, JavaScript uses Ajax to accomplish the task.
The above is only an overview. In essence, PHP customizes the web page at the server, before the page is sent to the browser. After the page is in the browser, JavaScript is used to customize the page.
(This content first appeared in Possibilities newsletter.)
Will Bontrager
