Sum an Array of Numbers with JavaScript

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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! The post Sum an Array of Numbers... more →
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How to Internationalize Numbers with JavaScript

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Presenting numbers in a readable format takes many forms, from visual charts to simply adding punctuation. Those punctuation, however, are different based on internationalization. Some countries use , for decimal, while others use .. Worried about having to code for all this madness? Don’t — JavaScript provides a method do the hard work for you! The Number primitive has a toLocaleString method to do the basic formatting for you: const price = 16601.91; // Basic decimal format, no providing locale // Uses locale provided by browser since none defined price.toLocaleString(); // "16,601.91" // Provide a specific locale price.toLocaleString('de-DE'); // "16.601,91" // Formatting... more →
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