It’s rare that I’m disappointed by the JavaScript language not having a function that I need. One such case was summing an array of numbers — I was expecting Math.sum
or a likewise, baked in API. Fear not — summing an array of numbers is easy using Array.prototype.reduce
!
const numbers = [1, 2, 3, 4];
const sum = numbers.reduce((a, b) => a + b, 0);
The 0
represents the starting value while with a
and b
, one represents the running total with the other representing the value to be added. You’ll also note that using reduce
prevents side effects! I’d still prefer something like Math.sum(...numbers)
but a simple reduce
will do!
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