Pet peeves:
.map() (or any other array iteration method like .filter, etc), in JavaScript for simply going through the array instead of .forEach() or a loop`. In general, use the array methods for their purpose:
.map - I have an array, I need another array where each item is based on the first one.flatMap - like .map but I use it when each new item also an array.filter - I have an array, I need less of it.find - I have an array, I need one item from it.findIndex - I have an array, I need the index of an item.some - I have an array, I need to check if at least one item passes a check.every - I have an array, I need to see if all items pass a check.forEach - I have an array, I need to do something with each item. Usually I don't want to return anything.reduce/.reduceRight - I have an array, I need to make it into "one value". I'll have to check if I really need to use reduce for thisfor, for..in, for..of, while, do..while loops if the problem can't (or doesn't need to) fit into one of the above