Add Client Script [Applying To - List]
// FOR CHILD TABLE FIELD
frappe.set_route('List', 'Task', 'List', {
'<Child Table Doctype>.<child_table_field>':"specify_child_table_field"
});
// FOR MAIN DOC FIELD
frappe.set_route('List', 'Task', 'List', {
'status':""
});
// ANOTHER WAY
frappe.listview_settings['Task'] = {
filters: [["status", "=", "Open"]]
}