Use Client script to get vendor bill id when vendor payment record is loaded.

Requirement is to get value of vendor bill id when vendor payment record is loaded.

/**
 * @NApiVersion 2.x
 * @NScriptType ClientScript
 * @NModuleScope SameAccount
 */
define(['N/currentRecord', 'N/record', 'N/url'],
    /**
     * @param{currentRecord} currentRecord
     * @param{record} record
     * @param{url} url
     */
    function (currentRecord, record, url) {
        /**
         * Function to be executed after page is initialized.
         *
         * @param {Object} scriptContext
         * @param {Record} scriptContext.currentRecord - Current form record
         * @param {string} scriptContext.mode - The mode in which the record is being accessed (create, copy, or edit)
         *
         * @since 2015.2
         */
        function pageInit(scriptContext) {
            try {
                var idFromUrl = window.location.href;
                var res = idFromUrl.split("&bill=");
                var billID = res[1].split("&")[0];
                console.log('billID',billID)
            } catch (e) {
                log.error('error@clientscript', e)
            }
        }

        return {
            pageInit: pageInit,
        };
    });