In Oracle Apex, use apex.item("ITEMNAME").getValue() or $v("ITEMNAME") JavaScript methods to get item value. Below are the examples:

Example 1: Get Item Value using apex.item().getValue() JavaScript Method

In the following JavaScript program, it will get the P2_TOTAL item value (total amount) in a variable n_amount:

var n_amount;
n_amount = apex.item("P2_TOTAL").getValue();

Example 2: Get Item Value using $v() JavaScript Method

The program will do the same task as above but using the $v() JavaScript method:

var n_amount;
n_amount = $v("P2_TOTAL");

Related Tutorials:

1. How to check if the item is empty/null using JavaScript in Oracle Apex?
2. Oracle Apex - Set Item Value Using JavaScript

Reference:

1. JavaScript API Reference for Oracle Apex