ask for a method in javascript prototype
//FactVal
UTIL.Classes.FactVal = function(entity, attribute, value) {
    this.entity = entity;
    this.attribute = attribute;
    this.value = value;
}

UTIL.Classes.FactVal.prototype.setEntity = function(entity) {
    this.entity = entity;
}

"FactVal": {
              "entity": {
               "string": "blabla"
              }
}

if(UTIL.Classes[i].("set" + j[0].toUpperCase() + j.substring(1,j.length)))

if(UTIL.Classes[i].("set" + j[0].toUpperCase() + j.substring(1,j.length)))

if(typeof UTIL.Classes[i]["set" + j[0].toUpperCase() + j.substr(1)] === "function")

if(UTIL.Classes[i].prototype["set" + j.charAt(0).toUpperCase() + j.substring(1,j.length)])

if(typeof UTIL.Classes[i].prototype["set" + j.charAt(0).toUpperCase() + j.substring(1,j.length)] === "function")

x = obj.foo;

x = obj["foo"];
// or
s = "foo";
x = obj[s];
// or
p1 = "f";
p2 = "o";
x = obj[p1 + p2 + p2];

FactVal.setEntity

Factval.prototype.setEntity

if( UTIL.Classes[i].prototype["set" + j[0].toUpperCase() + j.substring(1,j.length)] )

if (typeof URIL.Classes[i]["set" + (...)] === "function")