Questions tagged [javascript]

JavaScript (not to be confused with Java) is a high-level, dynamic, multi-paradigm, weakly-typed language used for both client-side and server-side scripting. Use this tag for questions regarding common implementations of ECMAScript, JavaScript, JScript, etc. JS does not typically refer to its ECMA-cousin, ActionScript.

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42 views

Messaging engine architecture with front-end and ORM layer (spring)

I'm looking to push my first QuickFixJ messaging engine into production, and I would like to know the best way to do so. Bear with me. The gist of the responsibilities is as follows: Through ...
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2answers
189 views

Is it bad practice to leave hidden elements in the dom?

I'm looking for perspectives from other web/ui developers. I'm a UI developer and my company requires that I use components built by another team within the company. That team has developed some ...
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3answers
175 views

If callback function, promises and async/await patterns all can be used to achieve asynchronous behaviour then why don't we stick to one?

As far as I have seen then async/await, callbacks and promises are and can only be used to achieve asynchronous programming. Correct? So my questions are: 1) Is it correct that the former three is ...
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128 views

What is the state of immutability in Javascript in 2019?

I'm all on board with functional programming in Javascript - particularly within the context of using React and Redux. Something that I've been running into again and again, is how easy it is to ...
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33 views

Extending prototype

I am currently refactoring a project where I come across the following kind of code multiple times: propertyFunction: function (feature) { doSomethingOnyWithFeature(feature); ... } Methods, that ...
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1answer
205 views

Difference between a strongly typed language and a weakly typed language with type annotations from the developer's point of view?

I understand that there are major technical differences between how a strongly typed language is compiled and how a type annotated language is compiled/transpiled. But as a developer writing in a ...
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1answer
254 views

What is the original reason JSON used `null` and not `undefined` to represent missing values?

In Javascript, there seems to be or have been an idea that undefined represents a missing primitive OR object value, while null represents just a missing object value. See, for example, this section ...
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1answer
58 views

Adding custom properties to Javascript Objects of external libraries - is that considered bad practice?

I regularily come across code that stores some custom properties in JS Objects from external libraries, for example: /**@param OpenLayers.Feature feature */ function doSomething(feature) { ...
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58 views

Two Web clients and Java server (HTTP and Websockets)

I have 3 software components of a Web Application: 1. JS-client application 1 (JSApp1) 2. Java Spring (REST and Websockets) server app (SRV) 3. JS-client application 2 (JSApp2) My current task is to ...
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1answer
460 views

How do functional programming advocates use a framework like React or Angular?

I read this blog post recently: The Two Pillars of JavaScript Part 1: How to Escape the 7th Circle of Hell, which is essentially a criticism of object oriented programming, and advocacy for funtional ...
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1answer
23 views

Geolocation client side requests: Key and ID storage

I'm developing a small web-app to help users manage shopping lists. One of the required features is the ability of the application to notify the user if a shop of the same category is near him/her. ...
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4answers
282 views

In Haskell, is it a “violation” of functional programming to interact with something that was not a function parameter?

I'm sure this must have been asked before, but I can't find anywhere that actually answers my question, so apologies if I have simply overlooked this. I am currently learning Haskell, and loving the ...
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100 views

Refactor MVC to more scalable architecture?

Months ago I began a new web project which, in the beggining, seemed like a small application with virtually few users. I began the project by using the awesome Hackathon Starter WebApp Boilerplate by ...
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1answer
37 views

Should I run my tests against production build transforms (i.e. Babel)?

A coworker of mine recently setup testing in a new project (a JS library) where a transform step hooks in to the babel config for Webpack in the production config. For reference, this is the setting ...
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1answer
145 views

Why (historically) do `+[] === 0` and `+{} === NaN` in Javascript?

In Javascript, converting [] to a number (e.g. +[]) gives 0, while doing the same to {} gives NaN. This leads to entertaining wats like this: > 2 / [] Infinity > 2 / {} NaN Is there a ...
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1answer
4k views

element.style.setProperty(property, value) vs element.style.property = value [closed]

I was wondering if I should use element.style.setProperty(property, value) or element.style.property = value. I am very much tempted to start using element.style.setProperty(property, value). But in ...
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1answer
4k views

Why doesn't v8 compile typescript instead of javascript? [closed]

Since Typescript is just a superset of javascript (every javascript program is also a typescript program), I've got this idea - why doesn't v8 support typescript? or anything statically typed ...
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23 views

How can I manage the state of my application using a dedicated object instead of what React offers?

Most of the react application I've seen are organized with components that, in my opinion, do too much. They may follow this pattern: class MyComponent extends Component { constructor() { ...
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5answers
8k views

Algorithm for flattening overlapping ranges

I am looking for a nice way of flattening (splitting) a list of potentially-overlapping numeric ranges. The problem is very similar to that of this question: Fastest way to split overlapping date ...
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5answers
1k views

Is it beneficial to study past the basics of a core language when the primary goal is to rely on its framework? [closed]

Please keep in mind this is not another 'How much [insert programming language here] should I know before moving onto [insert framework here]?' What I'd like to know is how beneficial is it to learn ...
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1answer
68 views

Uploading file to the server for download

I've my front end written using HTML/CSS/Javascript. Front end is communicating with the backend(Oracle database) using Java Webservices (Spring boot app). Situation #1: User clicks on the Download ...
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3answers
550 views

What does it mean to inject data (vs behaviour) in a class constructor, and why is that considered bad practice?

I am reading the book "Learning TypeScript" by Remo Jansen. In one section the author describes how to create a very simple proof-of-concept MVC framework including how to create the Model class and ...
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2answers
1k views

A real-life example of using curry function? [closed]

I was struggled to find a real-life example of using curry function and get the benefit of using curry. When I google curry function I often see the example like let add = x => y => x + y; ...
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1answer
213 views

Methods to Securing APIKeys

I have read on several methods to securing an API key like gitignore or placing in another file if using an application, but at some point if taken the time, anyone can get the key, even when apikey ...
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1answer
212 views

Split large Angular codebase to libraries

I am writing a potentially large web application using Angular 7, where I came across a design problem. My angular applications until now have been relatively small, so there was no problem keeping ...
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2answers
414 views

WebSockets vs Ajax call for scheduled event?

Intro I have been weighing the pros and cons of using WebSockets vs. an Ajax call for an event which will happen every x number of seconds (in this case 5). I'll start by explaining the scenario. ...
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1answer
121 views

What does await do in JavaScript?

Sorry for this naive question. Reading some existing JavaScript I see a function with code like ... async function _load() { await ensureDir(path); return await readFile(filename); } ... why ...
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7answers
77k views

try-catch in javascript… isn't it a good practice?

There is a provision for try-catch block in javascript. While in java or any other language it is mandatory to have error handling, I don't see anybody using them in javascript for greater extent. Isn'...
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1answer
59 views

How does event.target return the DOM object?

I read through documentation and searched on google, but couldn't find a specific answer. Currently, I have an object that subscribes to a click event. I am trying to understand how a view that ...
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3answers
526 views

Performance increase by only attach onblur handler inside of onfocus handler?

Given a web page with input fields, does it have a performance difference whether or not you assign the onblur handler inside of the onfocus handler like so: var inputFields = document....
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3answers
569 views

How can I prevent a user from editing my code in their browser?

Description I'm designing a Node.JS application (more like a full website). The app will send five JavaScript files and will have <script> tags linking them together. Question How can I ...
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2answers
47k views

Why does Javascript use JSON.stringify instead of JSON.serialize?

I'm just wondering about "stringify" vs "serialize". To me they're the same thing (though I could be wrong), but in my past experience (mostly with asp.net) I use Serialize() and never use Stringify()....
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3answers
740 views

“Comment everything the right way” and “Instead of writing comments, write more readable code.” - Both valid strategies?

When trying to learn about proper comment practices, I found a lot of conflicting opinions, and it's obviously a very subjective topic. So I'm not going to ask "Should I comment, or should I not?" ...
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2answers
73 views

Should / When to create javascript object to serialize data?

I'm working on a React/Redux application. I receive a data object from the api resembling this: const dataObj = [ { id: 1, name: "Filo", activity: 9, info: { statusCode: 4 ...
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3answers
283 views

What algorithm is used in subtitles?

What algorithm does a video player use to find the subtitles to show at any given time? I'm building a video player that displays some notes on different times over a video. Each note has a starting ...
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1answer
398 views

Would onpushstate be an anti-pattern?

In Single Page Applications, it's common to update the URL when navigating, and re-render based on the new URL. This can happen when the user hits the back and forward button, clicks on an anchor tag, ...
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2answers
845 views

How to write good javascript unit test descriptions

I come from a python background. I typically write long unit test descriptions that link the test to a user story. The test is as much about justifying why the code exists and how it fits into the ...
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1answer
162 views

Dealing with conditional verification logic using guard assertion

I have parametrized test with 2 variants: NULL value and any NOT NULL value From this value is depends one assert: In case NULL it should be checked if object has field1 with value1 In case ...
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1answer
64 views

Load files depending on browser or write workarounds within the file?

I'm writing up this website running under IIS with .NET Core. I developed most of the site with minimal use of JS so that the server will be doing most of the work (and thankfully so because of the ...
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2answers
341 views

When using Redux/Redux-Saga - should JWTs be set in the action creators/sagas?

Almost every blog post I've encountered around generic auth handling using JWTs in a React/Redux/Saga application does the same thing, which is to store the JWT in local storage, in the action/saga. ...
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3answers
139 views

Writing elegant promises in Node.js

I am having a real difficult time writing some clean code with a simple user registration/login manager. I am trying to stay out of nesting/callback hell, and am also not seeing any benefit in using ...
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1answer
82 views

Would I need a web framework if the app is running locally and not in the net?

I need to make an Employee Payroll application and the client specifically stated that the application will run on their computer locally and will not be hosted anywhere in the internet. I can code ...
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2answers
1k views

Terminology - Cache (Javascript)

I have watched a couple videos on JavaScript where the presenter mentioned "caching" a variable but I didn't see them do anything in the code that would "cache" it beyond normal assignments. When I ...
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4answers
929 views

in dynamic language like javascript how do you know what the argument is?

In Java or Scala if I have an argument configuration: Conf, I can look for Conf class/trait/case class and see its construct so I know which arguments to pass. Recently I started dealing with ...
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1answer
176 views

Using custom mime type for drag'n'drop events or data attribute dilema

I am having a dilema on a html/js application I have been requestyed to handle drag'n'drop events in order to display a dropped image in a div if is not from images that are already displayed in my ...
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1answer
206 views

Why are React keys limited to strings?

In React, when rendering a mapping from elements of a list/array/iterable to React elements, we're required to attach a locally-unique key to each element. Generally this is so that if an element ...
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1answer
57 views

continuous deployment of web application built with multiple packages

Our react web application is broken down to multiple components. Some of these components are part of the same git mono repo and some live in a different repo. Now, to implement a bug fix we have to ...
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1answer
113 views

What options are for a GUI for a Java application? [closed]

This might be a bit of a wide question. I have a couple of classes in Java that take input a String which is a mathematical expression and evaluates it. I want to implement a desktop GUI for this. ...
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2answers
97 views

Check or not objects in a Javascript API?

I'm writing an API in JavaScript, and I'm confused whether or not I should check if the API user is passing me the correct type on which the API expects to work. Actually not the type, but if you are ...
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4answers
405 views

JavaScript only validation on AJAX form submit

I've been mulling this question over for a few days in my head and I can't come to a solid answer. We understand that client side validation for forms is not enough, because you can easily turn ...