For example in lodash there is the _.assign method
However there is also the native Object.assign methods as well now that works more or less the same way.
The lodash assign and merge methods are two good examples of lodash object methods. They both do more or less the same thing but with just some note worthy differences. The merge lodash object methods will recursively merge down own and inherited object properties while the lodash assign will just assign properties. Also the merge method will skip source object properties that will evaluate to undefined, while assign will not skip them and just assign everything in the source objects.