JSFiddle - React, Tailwind, and code Playground

JavaScript

var object1 = {
    a: function () {},
    b: true,
    c: 0
};

var object2 = {
    a: function () {},
    b: function () {},
    d: function () {}
};

alert(getConflictingFunctionNames(object1, object2));

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;
}

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;
}