how to tell if a javascript variable is a function

Question

I need to loop over the properties of a javascript object. How can I tell if a property is a function or just a value?

var model = {     propertyA: 123,     propertyB: function () { return 456; } };  for (var property in model) {     var value;     if(model[property] is function) //how can I tell if it is a function???         value = model[property]();     else          value = model[property]; } 

Answer 1

Use the typeof operator:

if (typeof model[property] == 'function') ... 

Also, note that you should be sure that the properties you are iterating are part of this object, and not inherited as a public property on the prototype of some other object up the inheritance chain:

for (var property in model){   if (!model.hasOwnProperty(property)) continue;   ... }