Define function in attributes

[masalinas]

If try define a function inside an json attribute I obtain errors like: unexpected '('

For example:

[
{
"dataField": "codigoTrabajador",
"dataType": "dropdownbox",
"multiselection": false,
"filterRow": true,
"selector": true,
"caption": "Trabajador/a*",
"size": 6,
"valueExpr": "codigoTrabajador",
"displayExpr": (e: any) => {
return e && ${e.codigoTrabajador};
},
"validationRules": [
{
"type": "required",
"message": "Trabajador/a requerido/a"
}
]
},
]

With the attribute displayExpr obtin the previous error: unexpected '('. Is possible avoid this parsing errors when define functions like this?