utility to extract values at given paths from given objects

copyValues.js

// iteration 0
// adding deep diving for key paths
// based on getProperty()
// try on tddbin.com

function copyFrom(obj) {
  const values = (...keys) => keys.map(k => getProperty(k)(obj)); 
  return { values };
}

// "clone" of _.get, lets say.... @TODO make "setProperty" in the same fashion
function getProperty() {
    return compose(...mkGetters(Array.from(arguments)));
    // ES5:
    // var getters = mkGetters([].slice.call(arguments));
    // return compose.apply(null, getters);

    function mkGetters(args) {
        var keys = args;
        if (args.length === 1) {
            keys = args[0];
            if (!Array.prototype.isPrototypeOf(keys)) {
                keys = pathParser(args[0]);
            }
        }
        return keys.map(curry(get));
    }
}

function pathParser(path) {
    return path.split(/[\.\[\]]/g).filter(q => q !== '');
}

function curry(fn) {
    return function(arg) {
        return fn.bind(null, arg);
    }
}

var compose = (...fs) => (x) => fs.reduce((p,f) => f(p), x);

describe('mocha+assert API description', function() {
  
  it('simple values equal?', function() {
    // arrange
    var obj = { "a": 14, "b": 13, "c": 11 };
    // act
    var somevalues = copyFrom(obj).values("a", "c");
    // assert
    assert.equal(somevalues[0], 14);
    assert.equal(somevalues[1], 11);
  });

  it('deep values equal?', function() {
    var obj = { "a": { "a1": { "a2": 14 } }, "b": 13, "c": 11 };
    var somevalues = copyFrom(obj).values("a.a1.a2", "c");
    assert.equal(somevalues[0], 14);
    assert.equal(somevalues[1], 11);
  });
  
  it('sample usage', function() {
    
    var obj = { "a": { "a1": { "a2": 14 } }, "b": 13, "c": 11 };
    
    var keysToCopy = ["a.a1.a2", "c"];
  
    var somevalues = copyFrom(obj).values(...keysToCopy);
    
    // so now we have two arrays, one with the keys and one with the values
    // letsay later we have a v2 of "obj" and want to know if those keys have changed:
    var obj2 = { /* ... */ };
    
    var newvalues = copyFrom(obj2).values(...keysToCopy);
    
    var haveChanged = somevalues.some( (val, i) => newvalues[i] !== val );
    
  });

});