Detect whether method was called on object (javascript)

Question

This is a general programming question, not specific to this code example.

How do I detect whether a particular method was called or not from within a function?

Imagine you want to be able to tell whether a particular method was called so that you can change what you return based on that.

var turtle = function() {
    var vars = {
        name: "Shelly",
        age: 103
    };

    this.actions = function() {
        var methods = {
            crawl: function() {
                //etc...
            },
            mutate: function() {
                //etc...
            },
            eat: function() {
                //etc...
            }
        };

      if (methodWasCalled) { // <- The part I don't know how to do
          return methods;
      } else {
          return this;
      }
        
    };
    if (methodWasCalled) { // <- The part I don't know how to do
        return vars;
    } else {
        return this;
    }
};

Based on the above example, someone could use: turtle() and get access to the 'vars' object, or they could use: turtle().mutate() and the turtle object would execute the block inside that function.

why would you need to code in this manner? I imagine there's a better way so what is your use case — mistahenry
– mistahenry, Commented Jul 24, 2014 at 18:34
unfortunately, I can't talk about the specific use case, but if we use the turtle analogy what might you do differently? what about the example given seems inefficient or not as 'good'? — mmm
– mmm, Commented Jul 24, 2014 at 20:24

Cheruvian · Accepted Answer · 2014-07-24 18:25:19Z

1

To get the caller access the arguments object.

alert("caller is " + arguments.callee.caller.toString());

Callee refers to the function being executed, in your case mutate. It has a property that references the caller.

Best thing for you to do is break out a debugging kit (I personally prefer Chrome/IE) and explore the object to see the full details of info you want to see.

edited Jul 24, 2014 at 18:25

answered Jul 24, 2014 at 18:19

Cheruvian

5,9071 gold badge28 silver badges36 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Detect whether method was called on object (javascript)

How do I detect whether a particular method was called or not from within a function?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

How do I detect whether a particular method was called or not from within a function?

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related