Metro App - Call a Java Script method by name and send the list of params

In a Metro App that I writing in Java Script I wanted to call a function based on the method name that is send as a string. In C# we would need to use reflection but Java Script doesn’t require this think. We can very easily iterate through all the method like in an array and call our method.

obj[“”methodName ]();
obj[“”methodName ](param1, param2, …);

The above example get our method using “[…]” and after that calls our method. This is quite simple and a powerful feature.
But how we should rewrite this code if the parameters list are specified as an array. We want to be able to dynamically call any method and give a list of parameters as an array. If we try something like this:

var params = [param1 , param2];
obj[“”methodName ](params);

we will see that is not working, actually we set only the first parameter as an array, and the rest of parameters will be ‘undefined’. What should we do in this case is to use the apply method. Basically this method permits to specify the list of parameters as an array.

var params = [param1 , param2];
obj[“methodName”].apply(obj, params);

The first parameter need to be object of which the function is called. The second parameter is our array list. We can find another similar method named “call” that do the same think but without specifying the list of parameters (the function don’t have any parameter), but each parameter separately . The next 3 examples are equivalent for a function that doesn’t have any parameters:

obj[“methodName”].apply(obj);
obj[“methodName”].call(obj);
obj[“methodName”].();

or

obj[“methodName”].apply(obj, [param1]);
obj[“methodName”].call(obj, param1);
obj[“methodName”].(param1);

What we achieved? We are able to call dynamically any Java Script method based on a string name and an array of parameters.