Javascript

In working with collections (lists, queues, maps) of data, we usually have to perform one or more of the following operations on the collection: accessing, searching, appending, inserting, replacing/swapping, deleting and sorting Binary search is one of the most popular algorithms for searching for a number within a sorted list of numbers. It has a time complexity of O(log N) which means that its ability to find a number in a sorted list is minimally affected by the length of numbers in the list....

In a pet project that I worked on recently, one of the requirements was to allow users to submit the URL to their Facebook social media profile. This article describes how I ensured that only Facebook profile URLs were submitted. JavaScript was used but it does not matter as much as the algorithm used; and that algorithm is described here. function validateUrl(url, expectedOrigin) { const urlObject = new URL(url); const originPattern = new RegExp(expectedOrigin....

In building a house, after the architecture of the house has been drawn and accepted, everything built must fit the drawn architecture. A major change along the way may result in a complete tear-down and rebuild from scratch process. Once the building has been built with cement, it cannot be changed to wood. Building physical structures is a rigid process. Building software is different. Software, unlike physical structures, is expected to be flexible....

If one wants a function to be executed just after a period of time T in JavaScript, what do they do? They dump it in a setTimeout and surely, just immediately after T has elapsed, the function will be run. Right? Can you predict what happens when the code below is run? You should try it out in a Node.js REPL or the console. const extractTime = (date) => date.toTimeString().split(" ")[0]; var start = new Date(); console....

You know how you ask someone to call you back in a phone conversation? That’s what callback functions are. They are functions to be called later; after something has happened. In order to grasp this in practice, one needs to understand two things that there is a difference between a function name fn and a function call fn(), that functions can be passed into functions as arguments, the same way that numbers, strings and arrays are passed into functions as arguments The difference between a function name and a function call Let’s consider the code snippet below...

When you look at the second hand of a ticking clock, you’ll find out that the second hand moves sequentially. It points at 1 before it does 2, and then 3. It does not point at 4 and then 1 and then 9. Now imagine that the second hand is the JavaScript runtime and each number is a function. The second hand, which is our imaginary JavaScript runtime, determines what function runs by pointing at the number....

I was in a job interview pair programming session where I was asked to implement JavaScript’s setInterval method without using setInterval itself. I did poorly at that interview for many reasons, including not knowing how to implement this. The question Implement the setInterval function in such a way that executing new SetInterval.prototype.start will start the function passed to it and run the function at intervals interval until the SetInterval.prototype.clear method is called....