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!
![Convert XML to JSON with JavaScript]()
If you follow me on Twitter, you know that I've been working on a super top secret mobile application using Appcelerator Titanium. The experience has been great: using JavaScript to create easy to write, easy to test, native mobile apps has been fun. My...
![Detect DOM Node Insertions with JavaScript and CSS Animations]()
I work with an awesome cast of developers at Mozilla, and one of them in Daniel Buchner. Daniel's shared with me an awesome strategy for detecting when nodes have been injected into a parent node without using the deprecated DOM Events API.
![MooTools Window Object Dumping]()
Ever want to see all of the information stored within the window property of your browser? Here's your chance.
The XHTML
We need a wrapper DIV that we'll consider a console.
The CSS
I like making this look like a command-line console.
The MooTools JavaScript
Depending on what you have loaded...
![Use Custom Missing Image Graphics Using jQuery]()
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.jsmodule. Would it besum(nums)orsum(...nums)?sum([1,2,3])orsum(1,2,3)? I kinda prefer the latter.