Question

I have the following example code

var object = {
    userDefinedFunction : function(){
        //no implementation, this will be defined by the user
    }
}

What i want to achieve is the user giving his own implementation of it:

object.userDefinedFunction = function(){
    alert("just testing");
}

I tested this and works as i expected, what i want to know is:

• is this the javascript way of solving this kind of problem?

• let’s say that it’s mandatory that userDefinedFunction is implemented, how do i make sure of this? I could rely on something like the following, checking for implemented, but i’m learning javascript so i want to know how to leverage the language:

  userDefinedFunction : function(){
      implemented = false;
  }
  

Thank you.

Answer 1

var object = {
    userDefinedFunction : undefined,
    anotoherDefinedFunc : undefined,

    /* ... */

    hasUserImplementedInterfaces : function() {
        if (typeof object.userDefinedFunction !== 'function') return false;
        if (typeof object.anotoherDefinedFunc !== 'function') return false;
        /*  ... */
        return true;
    }

};

console.log(object.hasUserImplementedInterfaces());

hasUserImplementedInterfaces() function checks for user function implementations so you can execute as first check using that object.