gistfile1.js

function fromJS(anObject)
{   
    var objectsToReferences = new Map();

    return fromJS(anObject);

    function fromJS(anObject)
    {
        if (objectsToReferences.has(anObject))
            return objectsToReferences.get(anObject);

        if (isPlainObj(anObject) || Array.isArray(anObject))
        {
            if (Array.isArray(anObject))
            {
                result = I.List().withMutations(function(aList)
                {
                    objectsToReferences.set(anObject, aList);

                    R.forEach(function(aKey)
                    {
                        if (!isNaN(aKey) && parseInt(aKey) > 0)
                            aList.set(aKey, fromJS(anObject[aKey]));
                    }, Object.keys(anObject));
                });
            }
            else
            {
                result = I.Map().withMutations(function(aMap)
                {
                    objectsToReferences.set(anObject, aMap);
                    
                    R.forEach(function(aKey)
                    {
                        aMap.set(aKey, fromJS(anObject[aKey]));
                    }, Object.keys(anObject));
                });
            }
            
            return result;
        }
        
        return anObject;
    }
    
    function isPlainObj(value)
    {
        return value && (value.constructor === Object || value.constructor === undefined);
    }
}

What is R? I’m getting undefined.

Update: answering to my own question, it looks like Ramba.

https://gist.github.com/tolmasky/8a91af5ac1e0a949b423#file-gistfile1-js-L16
Missing var for result.

Otherwise, works as expected.

var obj = {}
obj.self = obj
var iObj = fromJS(obj)
iObj === iObj.get('self') // true

Immutable.fromJS(obj) // RangeError: Maximum call stack size exceeded