How to Dynamically Remove Sublist Line Items in NetSuite Client Scripts

To ensure successful removal of sublist line items, particularly from custom sublists, the logic should be placed within the PostSourcing client script event. While attempts to use the fieldChanged event for this purpose may not yield consistent results, PostSourcing reliably executes the necessary operations. The PostSourcing event is triggered after a field's value has been sourced, making it an ideal point to adjust related sublist data. The following SuiteScript 2.x example demonstrates how to clear all lines from a custom sublist with the ID custpage_rebate_discount when the 'customer' field is sourced or changed:

javascript
/**
 * @NApiVersion 2.x
 * @NScriptType ClientScript
 */
define(['N/currentRecord'], function(currentRecord) {
    function postSourcing(context) {
        var rec = context.currentRecord;
        var fieldName = context.fieldId;

        if (fieldName'customer')
        {
            while (rec.getLineCount({ sublistId: 'custpage_rebate_discount' }) > 0)
            {
                rec.removeLine({
                    sublistId: 'custpage_rebate_discount',
                    line: 0
                });
            }
        }
    }
    return {
        postSourcing: postSourcing
    };
});

This script leverages currentRecord.getLineCount() to determine the number of lines and currentRecord.removeLine() to iteratively remove them by always targeting the first line (index 0) until the sublist is empty.