Function isnullorEmpty

docs/app/js/sanddance-app.js:6231–6235

(value)

    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;
    return false;
}
class Exec {
    constructor(search, columns){
        this.columns = columns;