JavaScript Object Flatten

flatObj.js

function flatObj(obj) {
    if (!obj || typeof obj !== 'object' || obj instanceof Array) {
        throw new TypeError('flatObj() arguments need be object');
    }
    var result = {};
    for (var x in obj) {
        if (obj[x] && typeof obj[x] === 'object') {
            for (var y in obj[x]) {
                result[x + '_' + y] = obj[x][y];
            }
        } else {
            result[x] = obj[x];
        }
    }
    return result;
}