function thisIsBad ({ someKey: renamedSomeKey, someOtherKey: renamedSomeOtherKey = 'otherDefaultValue', meta: { innerMetaKey = 'someInnerMetaKeyValu

function thisIsBad ({ someKey: renamedSomeKey, someOtherKey: renamedSomeOtherKey = 'otherDefaultValue', meta: { innerMetaKey = 'someInnerMetaKeyValue', otherInnerMetaKey, ...remainingMeta } } = { someKey: 'defaultValue', someOtherKey: SOME_CONSTANT, meta: {} }) { // ... return { someKey: renamedSomeKey } } My favourite messed up part of the syntax is the way the `:` character is used to describe either the default value of a property or a way of renaming the name of a property internally (depending on whether it is to the left or right of an `=`). And also, the way you can destructure the inside of an object, and automatically lose the original value. For example `meta` is not accessible within the function defined above. This is syntax which can simplify your code if you apply it carefully, but will ruin your code if you over-use it.