Questions tagged [closures]

A closure represents a remarkable function that encapsulates and preserves variables from the specific scope where it was initially declared. Even when the defining scope concludes, if the closure persists, the variables it encloses will also persist, ensuring their continued existence.

JavaScript: Struggles with utilizing a function as an argument and later executing it inside a nested function

I've been struggling with defining a new function, and I need help resolving it. Here's an example that I was initially referencing: Pass arguments into ajax onreadystatechange callback? I wasn't able to find the solution through research, ...

Exploring the concepts of closure and scope

It seems that the function inResult always returns false and the loop is not being executed, probably due to a lack of understanding of closures. However, I can confirm that the result variable contains the correct properties. function hasId() {return ...

Master the Art of Animating Letters in the DOM by Navigating Through Any Array of Characters

I am attempting to implement a typewriter effect animation where a new message is displayed and animated as I type into an input box. Initially, I tried using a global char variable to iterate through each element of the array. However, whenever I passed ...

Closures are like the "use" keyword in PHP or the capture list in C++, but they play a similar role in JavaScript and other transpiler languages

PHP has a useful feature with the use keyword, which allows for the usage of 'external' variables in closures. For example: $tax = 10; $totalPrice = function ($quantity, $price) use ($tax){ //mandatory 'use' return ($price * $quantity) * ($tax + 1.0) ...

Exploring the power of jQuery closures and handling events like mouseover and mouseout

I'm currently grappling with the concept of utilizing closures in conjunction with jQuery event functions. The challenge I am facing involves creating rounded shapes on the screen that stop and fade when hovered over, then resume fading when the mouse mov ...

Creating a loop with resolves to navigate through states in AngularJS with ui-router requires the use of a closure

Within our AngularJS app, I am dynamically creating states using ui-router. Consider an array of states like the following: const dynamicStates = [ {name: 'alpha', template: '123'}, {name: 'bravo', template: '234'} ]; The process of building the ...

Exploring the Scope of a Directive within an HTML Element's Event Handler

I devised a custom Directive for utilizing an element as a 'dropzone' with native HTML Drag & Drop functionality. Custom Directive Source Code import { Directive, ElementRef, OnInit, Output, EventEmitter, ViewChild } from '@angular/core'; import { e ...

How is it possible to access a variable in a function that hasn't been declared until later?

While working on a Dialog component, I had an unexpected realization. export const alert = (content: string) => { const buttons = [<button onClick={()=>closeModal()}>ok</button>] // seems alright // const buttons = [<button onCli ...

Guide to specifying an explicit return type annotation for a recursive closure with JSDoc

In a project that utilizes vanilla JavaScript and type checking with tsc through JSDoc annotations, I have encountered a challenging use case. There is a function that returns another function, which may recursively call itself while also reassigning certa ...

The issue at hand is why the closure is not functioning properly when variables are assigned to the callback of the getCurrentLocation function

Apologies for the extensive amount of code, but it seems like there may be an issue with AppMobi's getCurrentLocation function in this scenario. The problem arises when tapping on list elements triggers an asynchronous getCurrentLocation call which updat ...

"Can you explain the process by which React grabs the props using the code `const props = this.props

I recently came across an interesting article authored by Dan. The example provided in the article caught my attention: class ProfilePage extends React.Component { showMessage = (user) => { alert('Followed ' + user); }; handleClick ...

The function in Swift that allows for escaping

I recently tried following a tutorial on YouTube that demonstrated how to retrieve data from a JSON file. However, I found some of the steps confusing. Here's the specific function being used: func fetchJSONData (completion: @escaping () -> ()) { ...

Is the functioning of closures identical when applied to class methods?

Recently, I started learning React.js (along with Javascript) and I have a basic question to ask. I have created a small component that consists of 3 buttons. Each time these buttons are clicked, the value increments by one. Here is a working example: cl ...

Can you suggest an alternative for the "return" statement within a "for loop" in order to retrieve all values from the loop?

When using numInOrder + " : " + nameInOrder;, the console only displays one value: "1 : a". However, I would like to see: "1 : a 2 : b 3 : c 4 : d 5 : e 6 : f" in the console.log output. Additionally, I do not want to use consol.log(numInOrder + " ...

What causes the closure variable to be reset after iterating over JSON data using $.each method?

Take a look at this scenario: var elements = []; $.getJSON(data_url, function(result) { $.each(result, function(key, value) { elements.push(parser.read(value.data)); // at this point, "elements" contains items }); }); dataLayer.addElements( ...

Preserving variable scope in JavaScript even after defining a function

I am facing an issue with my JavaScript code that involves invoking a function within a function: var obj = { // returns the function with prevent default prepended. run: function(functor, context){ return function(e){ e.preventDefault(); ...

Examples of Javascript closures in action with a for loop

I decided to stop my research here. Below is the question I have: After reading this post, I grasped the concept illustrated by the code snippet provided. var funcs = {}; for (var i = 0; i < 3; i++) { // creating 3 functions funcs[i] = functi ...

Exploring AngularJS $compile and the concept of scoping within JavaScript windows

I've encountered a scoping issue with the use of this inside an angular-ui bootstrap modal. The code below functions perfectly outside of a modal, but encounters problems when run within one: var GlobalVariable = GlobalVariable || {}; (function ...

Retrieving a local variable within an AngularJS controller

Examining the code provided below: app.controller('Controller', function($scope, $http){ $scope.rep = []; $scope.tot = { name: '', marketValue: 0, cash: 0, legend: 'none' }; (function loadData(){ ...

Addressing a particular scoping concern within jQuery

Often I come across this specific pattern. Could someone please provide me with a canonical method of ensuring that only image1 is displayed once? In example two, it works flawlessly - but the reason behind its success eludes me. Any insights or explanat ...

Organizing a NodeJS module - properties and functions

I've been struggling to structure my NodeJS application with modules, and after hours of searching, I haven't found a definitive answer. Let's say I want to create a "user" module for creating new users in my code: var newUser = new User(); ...