filter keys from an object

filterkeys.js

function filterKeys(obj) {
    var newObj = {}, key, url, i, newArr = [],
        disallowed = ['constructor', 'target', 'currentTarget', 'relatedTarget', 'srcElement', 'toElement', 'view'];
    for (key in obj) {
        if (obj.hasOwnProperty(key) && disallowed.indexOf(key) === -1) {
            if (Array.isArray(obj[key])) {
                newArr = [];
                i = obj[key].length;
                while (i) {
                    i -= 1;
                    if (typeof obj[key][i] === 'object') {
                        newArr.push(filterKeys(obj[key][i]));
                    } else {
                        newArr.push(obj[key][i]);
                    }
                }
                newObj[key] = newArr;
            } else if (typeof obj[key] === 'object') {
                newObj[key] = filterKeys(obj[key]);
            } else {
                newObj[key] = obj[key];
            }
        }
    }

    return newObj;
}