JavaScript is the original and common name applied towards most flavors of a scripting language that originated on NetScape Navigator. 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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116 views

“Python interpreter vs Javascript engine” memory model

I learnt that memory model of python interpreter is dictionaries of dictionaries, where each module is a dictionary. Let me elaborate more on this with an example, After i run >>> python ...
1
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1answer
142 views

React and simple UI state

I'm starting to playing around with React and have a basic question regarding state. I understand that in React state should only contain data which may change and cannot be computed from elsewhere, ...
3
votes
1answer
190 views

How do I design a Javascript Object to not use any public properties?

I have been playing with the Object creation outlined by Douglas Crockford in his new talk "The Better Parts" function constructor(spec){ var that = otherConstructor(spec), member, ...
1
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1answer
149 views

Keeping client side model and server side in sync in SPAs

Since SPAs have most of their domain logic client side, how do you keep your domain model in sync with the back end? For example, let's say I have a .NET WebAPI web service that uses the Entity ...
0
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1answer
170 views

How do I make a JavaScript promise return something other than a promise?

I have a spec from a client for an implementation of a method in a module: // getGenres(): // Returns a promise. When it resolves, it returns an array. If given an array of genres, ['comedy', ...
2
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1answer
120 views

In what case would indexedDB be useful [duplicate]

I have been over-viewing indexedDB recently, and I cannot seem to find a suitable use case that would not be better done using a server side database. Since the little hackathon competition I'm doing ...
-1
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1answer
167 views

How deeply can a JSON object be nested?

I was watching a video on a website that said json objects can be nested deeply. How far can a JSON object be nested before it will create an error?
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1answer
87 views

Trying to learn about core concepts in Javascript by making a web app, how can I do that without jumping to MVC frameworks? [closed]

For some reason I don't want to jump to a javascript MVC framework to make a web app for my portfolio. My main motive behind that is to learn in & outs of Javascript. What are my options if I want ...
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1answer
336 views

Correct usage of Bluebird promise

This is related to this question on promise performance. The current top answer states that using new Promise is an anti-pattern in bluebird And that promisify should be used instead. I ...
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2answers
153 views

Javascript inline event handling versus external jQuery event handlers

Working on a dynamic website that loads information from a JSON file and then populates the page with said elements. My question has to do with event handling - as of now, I don't see any reason as ...
0
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2answers
229 views

Is it OK to use Promises for Caching

Is it an acceptable (not surprising) to use promises to cache results? The idea is to generate a promise once, and just return that same promise again on subsequent calls. For example, a getAll() ...
15
votes
1answer
1k views

Why are native ES6 promises slower and more memory-intensive than bluebird?

In this benchmark, the suite takes 4 times longer to complete with ES6 promises compared to Bluebird promises, and uses 3.6 times as much memory. How can a JavaScript library be so much faster and ...
32
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3answers
3k views

How much should I be using 'let' vs 'const' in ES6?

I've been writing a lot of ES6 code for io.js recently. There isn't much code in the wild to learn from, so I feel like I'm defining my own conventions as I go. My question is about when to use const ...
7
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1answer
347 views

Language compiled to JS – most elegant way to do synchronous-style waits

I'm trying to make (yet another) language that compiles to JavaScript. One of the features I'd like to have is the ability to perform JavaScript's async operations synchronously (not exactly ...
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3answers
292 views

Is JavaScript fail-safe?

I was compiling a list of comparison of top 10 programming languages (JavaScript included). I was doing it from this Wikipedia page. However, in the third table (Failsafe I/O), there is no row for ...
1
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1answer
97 views

Multiple CS Sheets or Javascript

I have a homepage with a navigationBar on top of the Viewport contains two buttons. One is the default selected home button which calls/displays home.html. The other for example is Ubuntu which calls ...
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0answers
36 views

best/preferred way to create a “plugin” in JavaScript: “OOO” or array of each instance [duplicate]

I'm working on creating a "plugin" in JavaScript. I can't think of how to simplify my plugin's purpose so for the sake of simplicity let's say it is a table filter plugin. Either way the user would ...
1
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3answers
202 views

Avoid opt(options) in javascript [closed]

A lot of frameworks, most like jQuery plugins uses the "optional" parameter. Basically a dictionary (or key/value structure) with a bunch of additional parameters instead of send in the parameter's ...
1
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1answer
237 views

Best use of the React frontend framework

I've been using rails' erb template for my views, but I've recently been trying to incorporate React as my front end framework. I'm a little lost on how front end frameworks are supposed to be used. ...
3
votes
1answer
231 views

How can 'yield' be added as a keyword in ES6 if it wasn't a reserved word?

yield is not a reserved word in JavaScript, yet ES6 makes it a keyword. I thought the point of reserved words was for backwards compatibility. For example, let and const were reserved, so you ...
27
votes
6answers
4k views

Dynamic Code Evaluation in Java - Clever or Sloppy?

I am trying to create a flexible ACL framework in Java for my application. Many ACL frameworks are built on a whitelist of rules, where a rule is in the form of owner:action:resource. For example, ...
1
vote
5answers
472 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
vote
1answer
106 views

Checking for valid state inside function or outside [closed]

This is a common occurrence in programming and is language agnostic, you have a function that needs to do something but in only in some cases. Maybe it's a feature-toggle, maybe it's a function that ...
2
votes
1answer
151 views

Are web sockets a browser feature or supplied by a specific OS version?

Are web sockets a web browser feature, developed and evolving as the browser developers want, or this feature dependent on the OS version? For example, can I use this feature in JavaScript in IE and ...
2
votes
2answers
139 views

How hidden classes allows faster access to properties in google's V8?

As Lars Bak and Jay Conrod described in several videos and papers, the main idea of hidden classes in V8 is to store concrete offset or transition to another hidden class which probably contains this ...
0
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0answers
129 views

Choosing a javascript framework for a massively multi-player game : React vs Ember 2 vs other better option

I'd like to add to my Ruby on Rails app a javascript front end using basically Rails a json api sending data to the front end. The question for me is: React or Ember 2 (or maybe another viable ...
0
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1answer
156 views

Do you also find the use of functional reactive programming in JavaScript a bit overbloated? [closed]

I've been reading this article: http://modernweb.com/2013/09/30/functional-reactive-programming-in-javascript/ and I found the examples there way too complicated for what the code is supposed to do. I ...
0
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1answer
398 views

How to create a JSON or HTML file that dynamically mirrors file directory structure for jsTree 3.0 [closed]

I am looking to create a JSON OR HTML file that will accurately give the folder/file structure for a directory for use with jsTree 3.0 (www.jstree.com). I want to make it AJAX/lazy load so that each ...
0
votes
1answer
81 views

Personal Digital Signatures in Web Applications [closed]

In order to sign data with personal digital signature in a web application, server side languages like PHP can do the whole job, but that would require that the user uploads his private key, lets say ...
14
votes
3answers
2k views

why is the latter function 10% faster although it must create the variables over and over again?

var toSizeString = (function() { var KB = 1024.0, MB = 1024 * KB, GB = 1024 * MB; return function(size) { var gbSize = size / GB, gbMod = size % GB, mbSize = gbMod ...
7
votes
5answers
805 views

Why JavaScript? What's the advantages? [closed]

This is not a simple question, but I was thinking, what advantages are really there in the JavaScript language? We all use JavaScript on the browser, of course, there is no other choice (you can use ...
-1
votes
1answer
60 views

keeping of all javascript functions in one place [duplicate]

In php website I am using different javascript functions in different pages for example page a calls functions 1,2,3 and page b calls functions 2, 4, 6 and page c calls functions 3, 6 can I place ...
1
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1answer
160 views

Calculating winning probability for 2 teams using their history?

So I'm working on this project where I have a database full of team winning history. For example let's say these are all football teams. Every match has 2 participants (2 teams) and always a winner. ...
0
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1answer
143 views

Does streaming video pass through the website's server when embedded with javascript from another site?

Not sure how else to phrase this question, so my apologies if it's been asked before. We use Brightcove for streaming video. They offer an option to embed one of their players on your webpage using ...
0
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2answers
209 views

Is there any plan to take out “features” from next versions of javascript? [closed]

I'm looking to learn javascript (now for real) and I've had a look on the latest version of ES6 which is supposed to be frozen in terms of features set. It seems to be the pretty much same as ES5 ...
3
votes
2answers
189 views

Would there be any benefit to writing synchronous code using the syntax of promises

Is there such a concept as a synchronous promise? Would there be any benefit to writing synchronous code using the syntax of promises? try { foo(); bar(a, b); bam(); } catch(e) { ...
-3
votes
1answer
417 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 ...
2
votes
1answer
103 views

Need an algorithm to filter this collection format

I'm sorry the title is so vague ... I cannot think how to describe it any better. I have a collection in this format: var myCollection = [{id:"a"}, {id:"b",excludes:["a"]}, {id:"c",excludes:["b"]}]; ...
0
votes
0answers
54 views

Extension of native prototypes, good or bad practice? [duplicate]

Today I stumbled upon this page on the Mozilla Developer Network. In it, not only it is stated that it's a bad practice to extend native prototypes, but also that there is only one exception to this, ...
0
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1answer
184 views

Best Data structure for implementation of dependent drop-downs

I want to implement dependent drop-down feature on a web page in my website containing the following drop-downs: User's group name Group events (dependent drop-down) Locations (dependent drop-down) ...
1
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1answer
259 views

How to merge two functions that do same things with different variables

I have these two Javascript functions that are equal except for the variables onClickVoteUp: function (e) { var $target = $(e.target); var upvoted = this.model.get("upvoted"); var ...
5
votes
1answer
160 views

Is it poor decision making that using promises for GUI inputs?

So as you know the context: DOM with JavaScript, even though I think it is mostly a language agnostic issue (I know I put both language-agnostic and JavaScript tags, but it's only to let you see ...
3
votes
3answers
194 views

Anything wrong with direct evaluation of JSON if your own code created it?

Suppose I have a server-side variable containing JSON (named strJSON) that my own code created. In JavaScript I can consume it like this: var data = <%= strJSON %>; or use a JSON parsing ...
1
vote
2answers
137 views

Observer pattern: Prevent multiple firings on changed internal property

I have an object Foo that has 2 public properties: A and B. These properties can be changed from outside, as the application I'm working on is using a data-binding architecture. This is the ...
2
votes
1answer
146 views

Declaring JS Functions in Two Ways : What's the Benefit?

I've come across JS code in which I see functions being declared in two different styles: Method 1 function doSomething(){ alert('This is one way of declaring a function'); } Method 2 ...
1
vote
1answer
280 views

Assigning default values from environment variable in Node.js

When attempting to set default values for parameters that may exist in environment variables in JavaScript, I often see this pattern: var lag; try { lag = process.env.THROTTLE_LAG; } catch ( e ) ...
1
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0answers
199 views

Preserving Pre-formatted Multi-Line Strings in Node.js Scripts

There is a lot I don't like about PHP, but one thing I love is multi-line strings: $query = <<<EOT select field1 ,field2 ,field3 from tableName where field1 = 123 EOT; ...
26
votes
2answers
2k views

Is there any reason to use the “var” keyword in ES6?

Babel's guide to ES6 says: let is the new var. Apparently the only difference is that var gets scoped to the current function, while let gets scoped to the current block. There are some good ...
2
votes
1answer
111 views

How to deal with server-side and client-side naming conventions that clash? [closed]

I have a project that uses the underscore naming convention for the MySQL database and PHP scripts but uses camelCase for the javascript application (a common scenario I'm sure). However, once JSON ...
3
votes
3answers
462 views

With only backend development experience, how do I go into frontend development (js, html, css)? [closed]

Currently I am interning at a company as a "full stack" developer (Application developer on the job title) and I realize that I am having difficulties coping with frontend tasks. This is especially ...