Use ES6 class syntax

lib/cartodb/models/dataview/list.js

@@ -12,52 +12,50 @@ var listSqlTpl = ctx => `select ${ctx._columns} from (${ctx._query}) as _cdb_lis
     }
 }
 */
+module.exports = class List extends BaseDataview{
+    constructor (query, options = {}) {
+        super();
 
-function List(query, options) {
-    options = options || {};
+        this._checkOptions(options);
 
-    if (!Array.isArray(options.columns)) {
-        throw new Error('List expects `columns` array in widget options');
+        this.query = query;
+        this.columns = options.columns;
     }
 
-    BaseDataview.apply(this);
-
-    this.query = query;
-    this.columns = options.columns;
-}
-
-List.prototype = new BaseDataview();
-List.prototype.constructor = List;
-
-module.exports = List;
-
-List.prototype.sql = function(psql, override, callback) {
-    if (!callback) {
-        callback = override;
+    _checkOptions (options) {
+        if (!Array.isArray(options.columns)) {
+            throw new Error('List expects `columns` array in widget options');
+        }
     }
 
-    var listSql = listSqlTpl({
-        _query: this.query,
-        _columns: this.columns.join(', ')
-    });
+    sql (psql, override, callback) {
+        if (!callback) {
+            callback = override;
+        }
 
-    return callback(null, listSql);
-};
+        var listSql = listSqlTpl({
+            _query: this.query,
+            _columns: this.columns.join(', ')
+        });
 
-List.prototype.format = function(result) {
-    return {
-        rows: result.rows
+        return callback(null, listSql);
+    }
+
+    format (result) {
+        return {
+            rows: result.rows
+        };
+    }
+
+    getType () {
+        return TYPE;
+    }
+
+    toString () {
+        return JSON.stringify({
+            _type: TYPE,
+            _query: this.query,
+            _columns: this.columns.join(', ')
+        });
     };
-};
-
-List.prototype.getType = function() {
-    return TYPE;
-};
-
-List.prototype.toString = function() {
-    return JSON.stringify({
-        _type: TYPE,
-        _query: this.query,
-        _columns: this.columns.join(', ')
-    });
-};
+}