API Name: global.TableExtensionsProcessor

var TableExtensionsProcessor = Class.create();
TableExtensionsProcessor.prototype = Object.extendsObject(AbstractAjaxProcessor, {

/**
* Check if table extends another table.
*/

doesTableExtend: function() {
var tableName = this.getParameter('sysparm_table_name');
var baseTableName = this.getParameter('sysparam_base_table_name');
return this._doesExtend(tableName, baseTableName);
},

/**
* Check if table extends specified base table
*/

_doesExtend: function(tableName, baseTableName) {
var objectGR = new GlideRecord('sys_db_object');
objectGR.get('name', tableName);
var parentTable = objectGR.super_class;
while (parentTable) {
if (parentTable.name == baseTableName)
return true;

parentTable = parentTable.super_class;
}
return false;
},

type: 'TableExtensionsProcessor'
});