Netsuite – How to enter sublist items using a restlet

I am getting an error

{'error': {'code': 'JS_EXCEPTION',
  'message': 'org.mozilla.javascript.EcmaError: TypeError: Cannot find function selectNewLine in object standard record. (/SuiteScripts/NS Tests 2.js#67)'}} 

on trying to create a sales order record using a restlet.

My code below. How can I get it working?

/**
 * @NApiVersion 2.0
 * @NScriptType Restlet
 * @NModuleScope SameAccount
 */

define([
    'N/record',
], function(record) {
    function doPost(data){
    var recordObj = record.create({
        type: "salesorder",
        is_dynamic: true
    });

    var customer = data.customer;
    var tech = data.tech;
    var items = data.items;

    recordObj.setValue({
        fieldId:'entity',
        value:customer
    });
    recordObj.setValue({
        fieldId:'salesrep',
        value:tech
    });


    for (i = 0; i < items.length; i++) {
    recordObj.selectNewLine({
        sublistId: 'item'
        });

        recordObj.setCurrentSublistValue({
        sublistId: 'item',
        fieldId: 'item',
        value: items[i][0]
        });

        recordObj.setCurrentSublistValue({
        sublistId: 'item',
        fieldId: 'quantity',
        value: items[i][1]
        });

        recordObj.commitLine({
        sublistId:'item'
        });
    }
        var recordId = recordObj.save({
            enableSourcing: false,
            ignoreMandatoryFields: false
            });

        return recordId;

    }
    return {post:doPost};
});

Answer

Your is_dynamic should be isDynamic in record.create().