ton.js

/**
 *@NApiVersion 2.x
 *@NScriptType ClientScript
 */
define(["N/error"], function (error) {
  function round(num) {
    return Math.round((num + Number.EPSILON) * 100) / 100;
  }

  function fieldChanged(context) {
    try {
      var currentRecord = context.currentRecord;
      var sublistName = context.sublistId;
      var sublistFieldName = context.fieldId;

      log.audit("sublistFieldName", sublistFieldName);

      if (
        sublistName === "item" &&
        (sublistFieldName === "quantity" ||
          sublistFieldName === "item" ||
          sublistFieldName === "rate" ||
          sublistFieldName === "custcol_conversion_rate")
      ) {
        var convRate = currentRecord.getCurrentSublistValue({
          sublistId: "item",
          fieldId: "custcol_conversion_rate",
        });
        log.audit("convRate", convRate);
        if (convRate) {
          var quantity = currentRecord.getCurrentSublistValue({
            sublistId: "item",
            fieldId: "quantity",
          });

          log.audit("quantity", quantity);

          if (quantity > 0) {
            currentRecord.setCurrentSublistValue({
              sublistId: "item",
              fieldId: "custcol_total_in_ton",
              value: round(quantity * convRate),
            });
          }

          var rate = currentRecord.getCurrentSublistValue({
            sublistId: "item",
            fieldId: "rate",
          });
          log.audit("rate", rate);
          var ratePerTon = rate / convRate;
          currentRecord.setCurrentSublistValue({
            sublistId: "item",
            fieldId: "custcol_edc_rate_per_ton",
            value: round(ratePerTon),
          });
        }
      }
    } catch (err) {
      log.audit("Error", err);
    }
  }

  return {
    fieldChanged: fieldChanged,
  };
});