Function isStringOperation

docs/app/js/sanddance-app.js:6221–6230

(ex)

    return "";
}
function isStringOperation(ex) {
    switch(ex.operator){
        case "contains":
        case "!contains":
        case "starts":
        case "!starts":
            return true;
    }
    return false;
}
function isnullorEmpty(value) {
    if (value == null) return true; //double equal sign to also catch undefined
    if (typeof value === "string" && value.length === 0) return true;