Regular expressions are patterns used to match and/or manipulate strings. This is a high-level overview of a few of the practical applications of a RegEx in Javascript. What is RegEx and what’s it doing in Javascript? A RegEx consists of simple and special characters that together form a language of its own.

Use this if you want to repeatedly call a function for known arguments, or in case you just need a IIFE. If you want a repeatedly called functions, you would typically - Call function in a loop Use recursion For e.g. - 1 2 3 4 5 6 7 8 9 10 11 function printStr(str) { console.

Flatten arrays easily with a single command. Or, go further than that by using a map function while flattening arrays. Consider below example - 1 const nums = [[0, 2], [1, 3], [7, 9, 11]]; You can choose to iterate through all elements if you want to iterate through or access all numbers, or you could just use flat.

You should dynamically build strings without using strings. How do you build strings when you need them conditionally built? For example, you need comma separated planets from an array of astronomical bodies. 1 2 3 4 5 6 7 8 9 10 11 12 const astroBodies = [ { name: "earth", type: "planet" }, { name: "moon", type: "satellite" }, { name: "mars", type: "planet" } ]; let planets = ""; astroBodies.

Require and import do the same thing differently. I never said to none about missin’ the good ol’ days. The days when Javascript was not golden, code could be simply included within HTML or a single file, and when smarty-pants use to go cyber without Javascript. Those were more of WTF-days.

Object entries and values add to the rich toolset for managing objects within Javascript. As I never tire to say - (almost) everything is an object in Javascript. So, how do you access the props / values? It is not as if you are going to count them down - pfft.

It is quite common to use dot notation to access object’s props. How can you ever go wrong? We have seen a bit of dot and bracket notations in all about Javascript objects and props post. We have learnt to use dot notations to make our code more readable -

Be aware of hidden Javascript features that can break your code before you say “ugh..”. Consider the below code that prints today’s date - 1 2 3 const dt = new Date(); console.log("dt: ", dt); // 2019-03-31T13:56:42.552Z All looks good? Let us now create a target date for my payment - it is 1.

Someone once said “there shall be standards, and there were standards”. But no one said anything about consistency, uniformity, and stuff like that? The question is of course not about standards. Let me ask you this one thing - do you have any idea what’s going on with push and contact?

Be careful about using singleton patterns in Javascript classes. It may have unexpected side-effects and can be the most dreaded evil overlord you encounter on that day. Let us take this example of an Account class that is used by all logged-in users. Users set a role and are shown accounts based on the role.

Where does a comma fit in the class methods? No where. Where do I remember it from, then - Vue objects. When I started using Vue full time some time in 2017, I had this problem with putting commas everywhere. These were becoming like issues with semicolons - except that VS Code Prettier takes care of my semi-colons.

Promises and promise chaining - really powerful tools to use and make your life as easy as it can be. Until you are stuck in an error that no one seems to have a clue about. Let us see some common errors and how to fix them. 1. Not use error handling in promises It does not demand a lot, people.

A chain promises to process data through a promise-laden gold field. A simple promise - 1 2 3 4 5 6 7 8 9 10 11 let promiseToLog = new Promise(function(resolve, reject) { console.log("started"); setTimeout(function() { resolve("promise fulfilled.. after timeout"); }, 300); }); console.log("promise initialized"); promiseToLog.then(function(val) { console.log("resolver", val); }); As you have seen earlier the promise gets initialized and next statement (‘promise initialized’) gets executed without waiting to resolve promise.