map function for objects (instead of arrays)

Question

I have an object:

myObject = { \'a\': 1, \'b\': 2, \'c\': 3 }

I am looking for a native method, similar to Array.prototype.map

Answer 1

To responds more closely to what precisely the OP asked for, the OP wants an object:

myObject = { 'a': 1, 'b': 2, 'c': 3 }

to have a map method myObject.map,

similar to Array.prototype.map that would be used as follows:

newObject = myObject.map(function (value, label) {
    return value * value;
});
// newObject is now { 'a': 1, 'b': 4, 'c': 9 }

The imho best (measured in terms to "close to what is asked" + "no ES{5,6,7} required needlessly") answer would be:

myObject.map = function mapForObject(callback)
{
  var result = {};
  for(var property in this){
    if(this.hasOwnProperty(property) && property != "map"){
      result[property] = callback(this[property],property,this);
    }
  }
  return result;
}

The code above avoids intentionally using any language features, only available in recent ECMAScript editions. With the code above the problem can be solved lke this:

myObject = { 'a': 1, 'b': 2, 'c': 3 };

myObject.map = function mapForObject(callback)
{
  var result = {};
  for(var property in this){
    if(this.hasOwnProperty(property) && property != "map"){
      result[property] = callback(this[property],property,this);
    }
  }
  return result;
}

newObject = myObject.map(function (value, label) {
  return value * value;
});
console.log("newObject is now",newObject);

alternative test code here

Besides frowned upon by some, it would be a possibility to insert the solution in the prototype chain like this.

Object.prototype.map = function(callback)
{
  var result = {};
  for(var property in this){
    if(this.hasOwnProperty(property)){
      result[property] = callback(this[property],property,this);
    }
  }
  return result;
}

Something, which when done with careful oversight should not have any ill effects and not impact map method of other objects (i.e. Array's map).