True. Consider this example: props.removes[cc] !== props.last.margin TypeScript's strict types will see the error if the those are not the same data type

True. Consider this example: props.removes[cc] !== props.last.margin TypeScript's strict types will see the error if the those are not the same data type. A TypeScript aware editor will yell at me before I compile the code. Perhaps what I really wanted is: props.removes[cc][0] !== props.last.margin In JavaScript I would have to execute the code. If the code doesn't throw an error then I would have to examine the output to see if the resulting data structure matches what I expect. If not I have to run tests and track down the error. Then once the error is found and resolved I have to write unit tests for this scenario.