About a year ago I wrote a SuiteScript 1.0 class as a wrapper around the search functionality in NetSuite. I have updated the code over time, and I want to share the latest version. Among the new features is support for formulas and search expressions. The class should be backwards compatible with the original version, but in addition you can also pass an object to most functions, instead of passing separate parameters. This makes it more flexible and allows me to add more functionality.

Enjoy!

/**
 * Encapsulate NetSuite search functionality in an easy-to-use object for SuiteScript 1.0.
 *  
 * Version    Date            Author           Remarks
 * 1.0        11 Nov 2016     kmartinsson      Initial version
 * 1.5        06 Jul 2017     kmartinsson      Added record type to constructor
 * 2.0        23 Aug 2017     kmartinsson      Added Search2 function, with support for objects and adding multiple columns/filters
 * 2.0.1      01 Sep 2017     kmartinsson      Bug-fixes
 * 2.0.2      01 Sep 2017     kmartinsson      Fixed issue with join not being null, added hasOwnProperty check 
 * 3.0        20 Nov 2017     kmartinsson      Removed v1.x code stream, renamed Search2 to Search
 * 3.0.1      06 Dec 2017     kmartinsson      Added JSDoc style comments, updated comments to new JSDoc style
 * 3.0.2      28 Feb 2018     kmartinsson      Fixed bug in sort key which prevented proper sorting. Added alternative keys.
 * 3.0.3      15 Jul 2018     kmartinsson      Added filter expression support
 * 3.0.4      01 Oct 2018     kmartinsson      Added method removeColumns() for use on (external) saved search
 * 
 */

/**
 * Search object
 * @constructor
 * @param {string} recordtype - Optional NetSuite recordtype (internalid)
 */
function Search(recordtype) {
    this.recordType = null;
    this.columns = [];
    this.filters = [];
    this.filterExpressions = [];
    // Set internal id of saved search to null
    this.internalId = null;
    this.noSavedColumns = false;
    // If record type/ID is supplied, set it now, otherwise default to null
    if (recordtype != null && recordtype != "") {
        this.recordType = recordtype;
    }

    // Helper function to verify the value is empty or null
    function isNullOrEmpty(val) {
        if (val == null || val == '' || val ==[] || val == {}) {
            return true;
        } else {
            return false;
        }
    }

    
    /**
     * Remove all columns included in the search
     * @param none
     * 
     */
    this.removeColumns = function() {
        this.noSavedColumns = true;
    }

    /**
     * Add a column to include in the search
     * @param {object}|{string} column - Object specifying a column to return or string containing columnId
     * @param {string} join - Joined record (internalid) (optional)
     * @param {boolean}|{string} sorting - Sorting (optional)
     *         Options: true = descending, false = ascending, empty/null = no sorting, "yes" (ascending), 
     *         "no", "ascending", "descending" (can be abbreviated "a" and "d" respectively).
     */
    this.addColumn = function(column, join, sorting) {
            var nsSearchColumn = null;
            var paramColName = null;
            var paramJoin = null;
            var paramSummary = null;
            var paramSorted = null;
            // Check if first argument is string or object
            if (typeof column == "string") {
                paramColName = column;
                // Check if second argument is null (for no join)
                if (isNullOrEmpty(join)) {
                    paramJoin = null;
                    // Check if arguent for sorting was provided
                    if (!isNullOrEmpty(sorting)) {
                        paramSorted = sorting;
                    }
                } else {
                    // Check if second argument is boolean, then it is not 'join' but 'sorting'
                    if (typeof join == "boolean") {
                        paramSorted = join;
                        paramJoin = null;
                    } else {
                        paramSorted = sorting;//sorted;
                        paramJoin = join;
                    }
                }
                // Now paramJoin and paramSorted are assigned properly
                if (typeof paramSorted == "boolean") {
                    if (paramSorted == true) {
                        paramSorted = "des";
                    } else {
                        paramSorted = "asc";
                    }
                } else if (typeof paramSorted == "string") {
                    // Get first character of string, in lower case
                    var tmp = paramSorted.slice(0, 1).toLowerCase();
                    // y = ascending sorting, n = no sorting, a = ascending, d = descending
                    if (tmp == 'y' || tmp == 'a') {
                        paramSorted = "asc";
                    } else if (tmp == 'd') {
                        paramSorted = "des";
                    } else {
                        paramSorted = null;
                    }
                }

            } else {
                if (column.hasOwnProperty("name") && column.name != null) {
                    paramColName = column.name;
                } else if (column.hasOwnProperty("columnName") && column.columnName != null) {
                    paramColName = column.columnName;
                } else if (column.hasOwnProperty("columnname") && column.columnname != null) {
                    paramColName = column.columnname;
                } else if (column.hasOwnProperty("column") && column.column != null) {
                    paramColName = column.column;
                } else {
                    throw nlapiCreateError('search.addColumn() - Required Argument Missing', 'The required argument <em>columnName</em> is missing. This argument is required.<br>Received: ' + JSON.stringify(column));
                }
                if (column.hasOwnProperty("join") && column.join != null) {
                    paramJoin = column.join;
                }
                if (column.hasOwnProperty("summary") && column.summary != null) {
                    paramSummary = column.summary;
                }
            }
            nsSearchColumn = new nlobjSearchColumn(paramColName, paramJoin, paramSummary);
            // Check if 'sorted' value exists in object
            if (column.hasOwnProperty("sorted") && column.sorted != null) {
                // Get first 3 characters as lower case
                paramSorted = column.sorted.toLowerCase().substring(0, 3);
            } else if (column.hasOwnProperty("sorting") && column.sorting != null) {
                // Get first 3 characters as lower case
                paramSorted = column.sorting.toLowerCase().substring(0, 3);
            } else if (column.hasOwnProperty("sort") && column.sort != null) {
                // Get first 3 characters as lower case
                paramSorted = column.sort.toLowerCase().substring(0, 3);
            }
            if (paramSorted!= null && paramSorted!="") {
                if (paramSorted == "asc") {
                    nsSearchColumn.setSort(false);
                } else if (paramSorted == "des") {
                    nsSearchColumn.setSort(true);
                } else {
                }
            }
            // Check if 'formula' value exists in object, then add to column object
            if (column.hasOwnProperty("formula") && column.formula != null) {
                nsSearchColumn.setFormula(column.formula);
            }
            // Check if 'functionId' value exists in object, then add to column object
            if (column.hasOwnProperty("functionId") && column.functionId1 != null) {
                nsSearchColumn.setFunction(column.functionId);
                // Push new nlobjSearchColumn into array
            }
            // Check if 'label' value exists in object, then add to column object
            if (column.hasOwnProperty("label") && column.label != null) {
                nsSearchColumn.setLabel(column.label);
            }
            this.columns.push(nsSearchColumn);
            return nsSearchColumn;
        } // end function addColumn


    /**
     * Add multiple columns to include in the search
     * @param {array} columns - array of column objects
     */
    this.addColumns = function(columns) {
            for (var i = 0; i < columns.length; i++) {
                this.addColumn(columns[i]);
            }
        } // end function addColumns

    /**
     * Add a search filter
     * @param {object}|{string} filter - filter object or string containing fieldId
     * @param {string} fieldJoinId - field to use for join (optional)
     * @param {string} operator - operator for filter (optional)
     * @param {string} value - value to filter for (optional)
     */
    this.addFilter = function(filter, fieldJoinId, operator, value) {
            if (typeof filter == "object") {
                var obj = filter;
                var fieldId = obj.field;
                var fieldJoinId = null;
                if (filter.hasOwnProperty("join")) {
                    fieldJoinId = obj.join;
                }
                var operator = obj.operator;
                var value = obj.value;
                // Create filter object
                var nsSearchFilter = new nlobjSearchFilter(fieldId, fieldJoinId, operator, value);
                // Check if 'formula' value exists in object, then add to filter object
                if (obj.hasOwnProperty("formula") && obj.formula != null) {
                    nsSearchFilter.setFormula(obj.formula);
                }
                // Check if 'functionId' value exists in object,then add to filter object
                if (obj.hasOwnProperty("functionId") && obj.functionId != null) {
                    nsSearchFilter.setFunction(obj.functionId);
                }
                this.filters.push(nsSearchFilter);
            } else {
                var fieldId = filter;
                this.filters.push(new nlobjSearchFilter(fieldId, fieldJoinId, operator, value));
            }
        } // end function addFilter


    /**
     * Add multiple search filters
     * @param {array}filters - array of filter objects
     */
    this.addFilters = function(filters) {
            for (var i = 0; i < filters.length; i++) {
                this.addFilter(filters[i]);
            }
        } // end function addFilters

    /**
     * Add filter expression
     * @param {array} expression - array structure describing search expression
     */
    this.addFilterExpression = function(expression) {
        this.filters.push(JSON.parse(expression));
    }

    /**
     * Set filter expression - Replaces any existing filters
     * @param {array} expression - array structure describing search expression
     */
    this.setFilter = function(filterArray) {
        this.filters = filterArray;
    }
    
    /**
     * Set the type of record to search for
     * @param {string} type - internalid of record type to search for
     */
    this.setRecordType = function(type) {
            this.recordType = type;
        } // end function setRecordType


    /**
     * Use an existing saved search as starting point for this search
     * @param {string} internalid - internalid of existing saved search
     */
    this.useSavedSearch = function(internalid) {
        if (!isNullOrEmpty(internalid)) {
            this.internalId = internalid;
            // If internal id of a saved search is provided, load that saved search
            this.savedsearch = nlapiLoadSearch(this.recordType, this.internalId);
        }
    } // end function useSavedSearch


    /**
     * Return search results as a nlobjSearchResult object
     * @param {string} recordtype - Optional NetSuite recordtype (internalid)
     */
    this.getResults = function(recordtype) {
            var results = [];
            if (recordtype != null && recordtype != "") {
                this.recordType = recordtype;
            }
            if (this.internalId != null) {
                // If internal id of a saved search is provided, load that saved search
                var savedsearch = nlapiLoadSearch(this.recordType, this.internalId);
                // Add new filters to saved search filters
                var newfilters = savedsearch.getFilters().concat(this.filters);
                // If existing columns in saved search should not be use, replace then
                var newcolumns = [];
                if (this.noSavedColumns) {
                    savedsearch.setColumns(this.columns);
                    newcolumns = this.columns;
                } else {
                    // Add new columns to saved search columns
                    newcolumns = savedsearch.getColumns().concat(this.columns);
                }
                // Perform the search
                var newsearch = nlapiCreateSearch(savedsearch.getSearchType(), newfilters, newcolumns);
                // 
            } else {
                // Otherwise build the search ad-hoc and set columns and filters
                var newsearch = nlapiCreateSearch(this.recordType, this.filters, this.columns);
            }
            var resultset = newsearch.runSearch();
            // Loop through the search result set 900 results at a time and build an array
            // of results. This way the search can return more than 1000 records.
            var searchid = 0;
            do {
                var resultslice = resultset.getResults(searchid, searchid + 900);
                for (var rs in resultslice) {
                    results.push(resultslice[rs]);
                    searchid++;
                }
            } while (resultslice != null && resultslice != undefined && resultslice.length >= 900);
            return results;

        } // end function getResults

} // end class search