Find conflicting method names in two JavaScript objects

Question

I am trying to simulate multiple inheritance in JavaScript, so I need to find a way to obtain a list of conflicting method names for two JavaScript objects. Is it possible to generate a list of function names for two objects, and then find all of the function names that are the same between the two classes?

    function base1(){
        this.printStuff = function(){
            return "Implemented by base1";
        };
    }

    function base2(){
        this.printStuff = function(){
            return "Implemented by base2";
        };
    }

function getConflictingFunctionNames(object1, object2){
    //get a list of conflicting function names between the two objects. 

    //to be implemented.
}

console.log(getConflictingFunctionNames(base1, base2)); //this should print ["printStuff"]

I think I'll need to get a list of all methods in each object, as described here, and then find all the method names that are the same in both of them. http://stackoverflow.com/questions/2257993/how-to-display-all-methods-in-a-javascript-object — Anderson Green, Mar 11 '13 at 01:50
@ExplosionPills I fixed the mistake. I meant to write `"printstuff"`. — Anderson Green, Mar 11 '13 at 01:51
You don't need to get all the methods of both objects, you just need to get the methods of one object and check which ones the other object has. — RobG, Mar 11 '13 at 03:02

score 2 · Accepted Answer · answered Mar 11 '13 at 02:08

You'll need to follow the following steps:

Get all the own property names on each object.
Filter the functions.
Create a union of both the sets.

The first two steps can be combined into a single function:

function getOwnFunctionNames(object) {
    var properties = Object.getOwnPropertyNames(object);
    var length = properties.length;
    var functions = [];

    for (var i = 0; i < length; i++) {
        var property = properties[i];
        if (typeof object[property] === "function")
            functions.push(property);
    }

    return functions;
}

Next you need to find the union of the set of functions of two objects:

function getConflictingFunctionNames(object1, object2) {
    var functions1 = getOwnFunctionNames(object1);
    var functions2 = getOwnFunctionNames(object2);
    var length = functions1.length;
    var functions = [];

    for (var i = 0; i < length; i++) {
        var functionName = functions1[i];
        if (functions2.indexOf(functionName) >= 0)
            functions.push(functionName);
    }

    return functions;
}

Now you may do whatever you wish with these functions.

See the demo here: http://jsfiddle.net/gVCNd/

score 0 · Answer 2 · answered Mar 11 '13 at 03:00

If you just want to find the common named methods, then:

function getCommonNamedMethods(obj1, obj2) {
  var result = [];

  for (var p in obj1) {

    if (typeof obj1[p] == 'function' && typeof obj2[p] == 'function' ) {
      result.push(p);
    }
  }
  return result;
}

If you want only own properties of the objects, include an own properties test:

function getCommonNamedMethods(obj1, obj2) {
  var result = [];

  for (var p in obj1) {

    if (obj1.hasOwnProperty(p) && typeof obj1[p] == 'function' &&
        obj2.hasOwnProperty(p) && typeof obj2[p] == 'function' ) {
       result.push(p);
    }
  }
  return result;
}

Find conflicting method names in two JavaScript objects

2 Answers2

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