Sum an Array of Numbers with JavaScript
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!
![Responsive Images: The Ultimate Guide]()
Chances are that any Web designers using our Ghostlab browser testing app, which allows seamless testing across all devices simultaneously, will have worked with responsive design in some shape or form. And as today's websites and devices become ever more varied, a plethora of responsive images...
![From Webcam to Animated GIF: the Secret Behind chat.meatspac.es!]()
My team mate Edna Piranha is not only an awesome hacker; she's also a fantastic philosopher! Communication and online interactions is a subject that has kept her mind busy for a long time, and it has also resulted in a bunch of interesting experimental projects...
![Dynamically Create Charts Using jQuery Flot and Google Analytics]()
![Making the Firefox Logo from HTML]()
When each new t-shirt means staving off laundry for yet another day, swag quickly becomes the most coveted perk at any tech company. Mozilla WebDev had pretty much everything going for it: brilliant people, interesting problems, awesome office. Everything except a t-shirt.
That had to change.
The basic...
Initializing with 0 might not be necessary since it takes the value from the first item in the array if not provided (and then skips the first item for the rest). It’s very slightly slower to set it to 0.
Here’s what I wonder though… Suppose this were in some
math.js
module. Would it besum(nums)
orsum(...nums)
?sum([1,2,3])
orsum(1,2,3)
? I kinda prefer the latter.