I'm trying to create a client side script that populates a custom column field with a calculated value when one of the other transaction column field is changed. Right now I am using sublistChanged as the entry point and it is looping forever. @User I think I saw you answered a similar question on a forum

/*******************************************************************
 *
 *
 * Name: MMO_CUE_rateCard.js
 * @NApiVersion 2.x
 * @NScriptType ClientScript
 * Version: 0.0.1
 *
 *
 * Author: MMO_CUE_rateCard.js
 * Purpose: Sets correct rate based on the project, item, currency, location
 * Script: The script record id
 * Deploy: The script deployment record id
 *
 *
 * ******************************************************************* */

define(['N/currentRecord', 'N/search', 'N/ui/dialog'], function(currentRecord, search, dialog) {

  function sublistChanged(context) {
    var currentRecord = context.currentRecord;
    var sublistName = context.sublistId;
    var index = currentRecord.getCurrentSublistIndex({sublistId:sublistName});
    log.debug('index', index);

    if (sublistName = 'item') {


      var project = currentRecord.getCurrentSublistValue({
        sublistId: sublistName,
        fieldId: 'job'
      });
      log.debug('project', project);
      var item = currentRecord.getCurrentSublistValue({
        sublistId: sublistName,
        fieldId: 'item'
      });
      log.debug('item', item);
      var location = currentRecord.getCurrentSublistValue({
        sublistId: sublistName,
        fieldId: 'location'
      });
      log.debug('location', location);
      var currency = currentRecord.getValue({
        fieldId: 'currency'
      });
      log.debug('location', location);

      try {

        if (project != null && item != null && location != null && currency != null) {
          var rate = rateLookup(item, location);
          log.debug('rate', rate);
          var fxrate = fxLookup(project, currency);
          log.debug('fxrate', fxrate);
          currentRecord.selectLine({sublistId:sublistName,line:index});
          currentRecord.setCurrentSublistValue({sublistId:sublistName,fieldId:'custcolmdlz_rate_usd',value:rate});
          currentRecord.setCurrentSublistValue({sublistId:sublistName,fieldId:'rate',value:rate*fxrate});
          currentRecord.commitLine({sublistId:sublistName});
        }

      } catch (e) {
        log.debug('Error reads: ', e.name + e.message);
      }

      return true;

    }
  }

  function rateLookup(item, location) {
    var customrecordrate_card_matrixSearchObj = search.create({
      type: "customrecordrate_card_matrix",
      filters: [
        ["custrecordlocation", "anyof", location],
        "AND",
        ["custrecordservice_item", "anyof", item]
      ],
      columns: [
        search.createColumn({
          name: "custrecordlocation",
          label: "Location"
        }),
        search.createColumn({
          name: "custrecordcurrency",
          label: "Currency"
        }),
        search.createColumn({
          name: "custrecordrate",
          label: "Rate"
        })
      ]
    });
    var tempres = customrecordrate_card_matrixSearchObj.run().getRange(0, 1);
    log.debug('tempres', tempres);

    var temprate = tempres[0].getValue({
      name: 'custrecordrate'
    });
    log.debug('temprate', temprate)
    return temprate;
  }

  function fxLookup(project, currency) {
    var customrecordfw_proj_fx_rateSearchObj = search.create({
      type: "customrecordfw_proj_fx_rate",
      filters: [
        ["custrecordfw_proj_fx_rate_proj", "anyof", project],
        "AND",
        ["custrecordfw_proj_fx_rate_currency", "anyof", currency]
      ],
      columns: [
        search.createColumn({
          name: "custrecordfw_proj_fx_rate_proj",
          label: "Project"
        }),
        search.createColumn({
          name: "custrecordfw_proj_fx_rate_period",
          label: "Period"
        }),
        search.createColumn({
          name: "custrecordfw_proj_fx_rate_currency",
          label: "Currency"
        }),
        search.createColumn({
          name: "custrecordfw_proj_fx_rate_fx_rate",
          label: "Exchange Rate"
        })
      ]
    });
    var tempres = customrecordfw_proj_fx_rateSearchObj.run().getRange(0, 1);
    log.debug('tempres', tempres);

    var temprate = tempres[0].getValue({
      name: 'custrecordfw_proj_fx_rate_fx_rate'
    });
    log.debug('temprate', temprate)
    return temprate;
  }

  return {
    sublistChanged: sublistChanged
  };
});

your sublistChanged entrypoint triggers itself when it updates the line again

yeah, how can I prevent that?

fix your code so that it doesnt always run is the general answer

yeah what I mean is how do I add that filter/guard? I assume there's a way to check what has changed

pick your favored technique

yeah that makes sense but how do I return what has changed? I couldn't find it anywhere

you can only set fields with changed values instead of always

oh really.. ok now I really have no idea how to check that lol

pure code approach is to have a variable

man

thats also an option, its generally better for performance to not commit the line twice