Flatten a nested json into a plain json

flattern-object.js

var handlers = {
    Object: flattenObject,
    Array: flattenArray,
};

function router(val, store, prefix, i ) {
    var kind, handler, key = prefix? prefix + '.'+ i : i; ;
    if( val === undefined || val === null ){
        return store[ key ] = val;
    }
    kind = val.constructor.name;
    handler = handlers[kind];
    
    if (handler) {
        return handler(val, store, key);
    }
    
    return store[ key ] = val;

}

function flattenObject(obj, store, prefix) {
    var i, val, kind, handler;
    for (i in obj) {
        router( obj[i], store, prefix, i );
    }
}

function flattenArray(obj, store, prefix) {
    var i=0, l = arr.length;
    while (i < l) {
        router( arr[i], store, prefix, i );
        i++;
    }
}

function flatten( obj ){
    var out = {};
    flattenObject( obj, out, '' );
    return out;
}