Array sum polyfill - Back to all questions
The challenge
Best suited for: Junior | Senior Stage: Round 2 | Onsite
You might have to add all items in an array of numbers. You have been keeping up to date with new stuff in JS but are not sure that sum() is part of the Array prototype methods.
Write a small program that will add all the items in an array of numbers and return the total using the Array sum function if it exists or using your custom function.
// should output 21
[1,2,3,4,5,6].sum();
// should be chainable and also output 21
[1,2,3].concat([4,5,6]).sum();
The context
Extending native objects is usually frowned upon in JS circles. This should stir a ‘healthy’ debate on the pros and cons of doing so. Ultimately, it should highlight the candidate awareness of safeguarding against potential existing and future functionality override.
I believe it’s a good question for a code screening or the first question on an onsite interview.