lodash merge that doesn't modify the source object

immutableMerge.js

_.mixin({
    'immutableMerge': function(src, dest) {
        return _.merge(_.cloneDeep(src), dest);
    }
});
 
// usage
 
var src = {
    a: 1, 
    b: 2
};
 
var dest = {
    c: 3,
    d: 4
};
 
var merged = _.immutableMerge(src, dest);
console.log(src, dest, merged) 
 
// { a: 1, b: 2 } { c: 3, d: 4 } { a: 1, b: 2, c: 3, d: 4 }

nice!