I'm looking for a way to catch Exceptions when accessing missing properties in the object itself.
I'm looking for something like:
var objOne =
{
objTwo: {},
objThree: {},
fallback: function(missingProperty)
{
alert('obj did not contain property ' + missingProperty);
}
}
Calls like objOne.objFour should be linked to objOne.fallback('objFour').
Is there a good way to handle this?
Accessing an undefined property does not trigger any exception, you can have the same behaviour with ||:
function callBack (missingProperty) {
alert('obj did not contain property ' + missingProperty)
}
objOne[attr] || callBack(attr);
This will trigger the callBack function when objOne does not contain attr.
the idea i have is to modify the constructor of the prototype of your customObject (for example objThree) and check for set values etc...
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/constructor
http://www.w3schools.com/js/js_object_definition.asp
or you define a custom event which is fired by creating an object:
https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Creating_and_triggering_events
i hope i understood you correctly and this is what you are searching for. Other possibility would be:
var objThree = function(a, b){
var parent = this;
this.valA = a;
this.valB = b;
this.checkForValues = function(){
if (parent.valA == null || parent.valB == null) return false;
return true;
}
greetings
