How to incorporate JavaScript into your application in Oracle APEX

There are a few ways to include Js code  in the Oracle application
1) Add Js code to the header in the page
2) Add Js code to the Function and Global Variable Declaration in the page
3) Upload the js file to the shared components static application files or static workspace files, add the file to the file URLS in the page.
#WORKSPACE_FILES#textfield#MIN#.js
Go to the page item: P9_ENAME
Advanced：
Customer Attributes： Onchange="displayValue('P9_ENAME')"
4) Use the dynamic action, execute Js code :
alert('ENAME='+ $v('P9_ENAME'))  
or
alert( 'ENAME='+ apex.item('P9_ENAME').getValue())