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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15
votes
1answer
5k views

Why doesn't ES6 have thin-arrow functions?

ES6 added fat-arrow functions (=>), which have two major differences from normal functions: shorter syntax (including implicit return if you use a single-expression body) inherit this from ...
1
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1answer
52 views

Dynamic execution of Template Literals using a Map

I have a system that is generating internal events for objects. I am extending their debugger to display a human-readable version of the events sent to the debugger. For instance, the system will ...
0
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1answer
251 views

Organizing reducers in Redux

I will use the following popular todo list example for demonstration. Let's say I wanted to create a very basic todo list with this structure as the app state: { todos: { todoKey1: { ...
6
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1answer
726 views

Order and filter Server-Sent-Events in angular.js eventsource

I have a Client in AngularJS where I consume multiple SSE (Server-Sent-Events) in Java from the Server Side (there are multiple endpoints in different web servers in the backend). Diagram link I ...
2
votes
1answer
808 views

Collecting user input to use as query with API

I'm attempting to collect the user's input and execute a search using an API. At this point, I can use the API (ebay search) by typing keywords into the html document- but I want the user to be able ...
1
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0answers
146 views

are magic strings as event names okay

I am about to create my own event-driven API in JavaScript. Most JavaScript that currently exists, e.g. in-browser JS for controlling the DOM, lets you register event handlers like this: object.on('...
3
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2answers
2k views

Linking service and factory functions to controller $scopes in AngularJS

I'm trying to keep my controllers as thin as possible, so I keep my domain logic in services and factories. When I need to call a function in response to a user action like a click I assign the ...
25
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5answers
3k views

Is rejecting a Promise only for error cases?

Let's say I have this function authenticate that returns a promise. The promise then resolves with the result. False and true are expected outcomes, as I see it, and rejections should only occur in an ...
2
votes
5answers
4k views

why are globals bad in javascript [duplicate]

I've been writing web applications for a while now , and everyone knows the one golden rule not to assign variables to the window object , don't ever assign a variable without using var. My ...
-1
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3answers
163 views

Why are framework javascripts not reutilised between pages?

As some js files are very common and widely used on the web, why browsers don't reutilise them? wouldn't it improve efficiency, as js framework files are usually heavy?
2
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1answer
54 views

Design Pattern to implement a settable JavaScript Module variable

I am writing a client to talk to a server API in JavaScript. I have an OOP background but am trying to embrace modern EcmaScript. So I started with this: customerApi.js: const baseUrl = "http://...
2
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2answers
82 views

API Race conditions

I have an API in which we expect a emailID and a certain deal data. The case is we want to keep the dealId and contactId(email) to be unique. Creating a deal requires data insertion in multiple ...
0
votes
0answers
59 views

Allowing a user on one page to be able to cause an event on another

I would like to allow a set of users to be able to submit a form on one page, and then it would cause an event to trigger on another page. For example: Submit Page: Includes the form, the user ...
1
vote
4answers
268 views

Writing C# utility that checks on property

I have a business requirement that requires checking on a person's first name to ensure it does not have the character "1". The model: public class Person { public string FirstName { get; set;...
-3
votes
1answer
74 views

How compiler and interpreter both are used in one language? [closed]

After writing the complete code the compiler compile the whole code at a time , but on the other hand interpreter take single line at a time. Both the compiler and interpreter are mostly called the ...
-1
votes
1answer
81 views

Is it a bad idea to persist a javascript function?

I'm working on eventual consistency. In short I have a bunch of promises and I want to make sure they get retried until they succeed. It would make my life a lot easier if I could just persist the ...
1
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2answers
103 views

How to write unit tests a method with a result that is highly based on another method [duplicate]

How to write unit tests a method with a result that is highly based on another method ? async function getStatus( session, correlationId, data ) { const client = new SomeAPIWrapperClient({ ...
2
votes
1answer
31 views

handle file downloads from the server

I am wondering if the following would be a good technique to allow user to download files from the server in the below scenario: Info about the scenario: User logs into a system (HTML,JQuery and CSS,...
2
votes
1answer
197 views

Which programming pattern is best for checking which partition a number lies in?

I have an interval partitioned into “MECE” subintervals, and I want to check which subinterval a number lies in. (MECE stands for “mutually exclusive & collectively exhaustive”, meaning the ...
1
vote
1answer
65 views

ES6 - Where is it better to initialize a member - parent class or derived class?

I am trying to figure out if there is a better practice for initializing class members of derived classes in ES6 - in the child or the parent, and why? For example: Option 1: class AbstractAnimal {...
34
votes
3answers
20k views

Any point in using ES6 Map when keys are all strings?

Plain object keys must be strings, whereas a Map can have keys of any type. But I have little use for this in practice. In nearly all cases, I find myself using strings as keys anyway. And presumably ...
1
vote
1answer
109 views

Should a function implementer or function caller handle immutability

I know there is no right and wrong answer here, I'm just looking for other opinions on who should handle immutability, dependency inversion and decoupling. Example 1: Here each function caller has ...
6
votes
2answers
3k views

React: Nested object as state vs individual properties

Are there any use-cases where a nested object as state is either more optimal/easier to work with than individual properties? For instance if I wanted to express some user controls for interacting ...
0
votes
2answers
79 views

Website Multi Languuage [closed]

I have one website and the website are now in HTML, that actually is structured: domain.com = English domain.com/es = Spanish domain.com/de = Germany I copied the HTML of English page to Spanish ...
1
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1answer
96 views

How function parameters are compiled in JavaScript

I am trying to understand how functions -- which could have dozens of parameters that could themselves be functions or complex objects (I'm thinking JavaScript) -- get passed the arguments when ...
2
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0answers
38 views

Dynamic API Data Validation

I am in the process of building an heavily data-driven web application written in Node.js / Typescript with Mariadb for the database engine. I am trying to put an emphasis on extensibility and DRY ...
1
vote
4answers
99 views

filter + map api design

I am writing a library call that will allow you to filter and map in the same iteration of the loop, this is async/callback style in Java. The problem of course is that for filtering we usually return ...
1
vote
2answers
310 views

Avoid if-else block in favor of default assignment followed by if

A colleague, and frankly better software engineer that me, is telling me that this pattern let variable = someDefaultVariable(); if (some_boolean) { variable = someOtherValue(); } is better than ...
4
votes
1answer
2k views

Microservices Architecture separating backend and front end

We are trying to move (slowly) into Microservices architecture from our current monolithic based architecture. I've done my research on microservices architecture and would like to get some feedback ...
-1
votes
1answer
111 views

RPC with Express JS? [closed]

I've been working on a project recently where I have an Expressjs server that supplies weather forecast data to its clients. Right now, I'm using express simply as a means of exposing some functions I ...
1
vote
0answers
38 views

Best practices for positioning elements in an HTML-based game

It seems like HTML5 has about a zillion different layouts and methods for positioning divs, few of which seem to work exactly as described in most browsers. Imagine an implementation of, say, Tetris ...
1
vote
1answer
64 views

Efficient and readable method for styling of javascript webcomponents

I have a web page that loads a very long list of custom web components, each with their own shadow DOM and a stylesheet shared by all instances. Originally, I included the stylesheet as css file ...
-1
votes
1answer
125 views

Does avoiding Promises and Async leads to clean code?

While applying for a job interview I found this line in requirements. Experience with clean code writing practices like avoiding callback hell like promises, async Does this line make any sense ? ...
0
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0answers
35 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 ...
1
vote
2answers
167 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 ...
0
votes
3answers
159 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 ...
2
votes
0answers
119 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 ...
0
votes
0answers
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 ...
0
votes
1answer
158 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 ...
0
votes
1answer
156 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 ...
0
votes
1answer
57 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) { ...
0
votes
0answers
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 ...
1
vote
1answer
395 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 ...
1
vote
1answer
22 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. ...
1
vote
4answers
277 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 ...
1
vote
0answers
90 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 ...
1
vote
1answer
35 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 ...
1
vote
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 ...
1
vote
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 ...
6
votes
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 ...