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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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 ...
3
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1answer
5k 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 ...
6
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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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0answers
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() { ...
16
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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 ...
10
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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 ...
0
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1answer
70 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 ...
10
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3answers
606 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 ...
8
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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; ...
2
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1answer
306 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 ...
2
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1answer
322 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 ...
0
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2answers
477 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. ...
0
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1answer
157 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 ...
69
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7answers
79k 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
61 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 ...
2
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3answers
558 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....
11
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3answers
611 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 ...
18
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2answers
48k 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()....
6
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3answers
767 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?" ...
0
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2answers
75 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 ...
1
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3answers
307 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 ...
1
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1answer
428 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, ...
3
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2answers
950 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 ...
3
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1answer
167 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 ...
0
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1answer
66 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
430 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
169 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 ...
3
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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 ...
7
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4answers
945 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 ...
0
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1answer
193 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 ...
0
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1answer
334 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 ...
2
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1answer
64 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
120 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. ...
0
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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 ...
2
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4answers
428 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 ...
2
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1answer
146 views

Best practice for REST result payload when field may have single or multiple values

I Have a REST API endpoint where the caller can supply some optional filters for the results. GET api/inventory For example, an object member of a GET request may look like the following { "...
2
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1answer
124 views

How should I define hardcoded strings with some variable parts? Reuse more characters? Or keep the whole sentence?

for example, sometimes I need to define a hardcoded string with some variable parts, I often have trouble to choose the style: style 1 : reuse every characters when possible showMessage(num){ let ...
6
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2answers
2k views

Memory usage of JavaScript string type with identical values

JavaScript string type is immutable, but does it mean identical strings will share memory? Say two strings are created in complete different places, will a modern JavaScript engine be smart enough to ...
-1
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2answers
285 views

How to process a login form data?

I have created a login form for my website, but the issue is how to process the data provided in the form by the uses. You see, I can't just write a basic function like this one - myfunction(){ if(...
2
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2answers
116 views

An options parameter vs chained functions for object initialization?

What concrete objective advantages do chained functions have vs an options parameter for object initialization? What do I mean? Well as one example there's a library called dat.GUI that uses the ...
1
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1answer
117 views

OrderedMap or List for Redux structure?

I'm implementing a Redux store for a React app using redux-saga for API calls. I've used Immutable.js before for other Redux-using React apps but the nature of previous projects always evidently ...
3
votes
2answers
571 views

What is the right time to go for Code Refactoring, not optimization?

I've been working on a Python(Django)/JavaScript(AngularJS) based application for some time now.(I learnt all of these on the way, had previously been a Java only programmer)and have hit moments where ...
1
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2answers
1k views

Supporting multiple javascript frameworks in eventual single application

We are building several applications that will eventually be one front-end application. It is split up into several projects at the moment where each project is managed by its own scrum team. The ...
0
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1answer
118 views

How to build a data-driven menu in JavaScript?

I'm going to attempt to build a data-driven menu for my web-app. The goal is to be able to serve different menu options to different users from an API. The hope is that the server could return a ...
3
votes
1answer
304 views

What's the best way to handle a large multi-file class in Javascript?

I have a very large class of 59 methods and about 3000 lines of code. I know that's far larger than most people would want, but the class represents a virtual machine, and most of the methods are run ...
0
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0answers
31 views

Promise, Ecmascript and Whatwg event loop

I've recently learned that setTimeout is not part of Ecma 262 standard but takes part of WhatWG one. I have one misunderstanding concerning these two standards and I can't get how they converge. For ...
0
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1answer
44 views

Can websites written in JavaScript make requests to SOAP API's?

I have an API written in SOAP 1.2 that I am trying to give to a developer whose website is written in Javascript and said they can not request the file because they do not know PHP. From my ...
1
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1answer
143 views

Strategy to deal with huge data

I have a Spring based java webservice which is returning JSON response. The problem is that the JSON response takes long time because the SQL involved is querying huge chunk of data and it takes 4-5 ...
10
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5answers
80k views

Falsy values vs null, undefined, or empty string

I've worked with jQuery over the years. However, recently, I've found myself getting deeper into the JavaScript language. Recently, I've heard about "truthy" and falsey values. However, I don't fully ...