A touch of javascript with a dash of underscore:
_.mixin({
extendNonNull: function(obj) {
_.each(_.rest(arguments,1), function(source) {
if (source) {
for (var prop in source) {
if( _.isObject(source[prop]) && _.isObject(obj[prop])){
obj[prop] = _.extendNonNull(obj[prop], source[prop]);
}
else if( !_.isNull(source[prop])){
obj[prop] = source[prop];
}
}
}
});
return obj;
}
});
var original = {a:1, b:2, c:3, d:{g:1}};
var fresh = {a:5, b:null,c:"", d:{e:4,f:5,g:null}};
var mixed = _.extendNonNull(original, fresh);