News Articles arrow-functions

Get the `value` or `textContent` of element when using arrow function binding REACT

I am asking this question out of curiosity. I want to get the value of an element that fires an event in REACT when I bind the event handler using the arrow function in es6 Class-Based Component //event handler function clickHandler() { console.log(this.textContent); } //the JSX Component element <div className="first-row d-flex"> <button className="button flex-child" data-id="AC" […]

What does "=>{}" mean in JavaScript?

Can someone kindly explain in simple terms what =>{} means in JavaScript? I have tried googling it but I kept getting irrelevant responses. For example: componentDidMount() { axios.get("https://jsonplaceholder.typicode.com/posts"); .then(response =>{}) } Source: JavaSript – Stack Overflow

What is the lexical environment inside a callback function?

I keep hearing that arrow functions inherit the value of this from their Lexical Environment. So, in this example: let para = document.getElementById("para"); let article = document.getElementById("article"); article.addEventListener("click", () => { console.log("I’m a span tag!"); event.stopImmediatePropagation(); }); para.addEventListener("click", () => { console.log("I’m a p tag!"); }); <p id="para"> <span id="article">Click Me!</span> </p> Why is the […]

Arrow functions in object literal vs arrow functions in class generated objects [duplicate]

const objectLiteral = { x: 5, getX: () => { console.log(`The value of x is ${this.x}`); } } x.getX(); // The value of x is undefined Why this doesn’t bind to the getX method when I use an object literal? Doesn’t the arrow function get their this from the parent scope? In this case the […]

mouseover not working as an arrow function?

I have the function below: .on("mouseover", function(d, i) { d3.select(this) .attr("fill", "red"); }) However, I wanted to try writing it as an arrow function, so I found that this tutorial and got this: .on("mouseover", (d, i, nodes) => { d3.select(nodes[i]) .attr("fill", "red"); }) However, whenever I try running it, I keep getting an error that […]

How can I pass this normal function to an Arrow Function [closed]

I wanna pass this normal function to an arrow function: let comparaComThis = function (param){ console.log(this === param) } comparaComThis(global) I’ve tried this example here, but it didn’t work..: let comparaComThis = (param) =>{ console.log(this === param) } comparaComThis(global) Source: JavaSript – Stack Overflow

How to convert from react component to arrow function

I was trying to convert the React component below to arrow function. import { Jsme } from ‘jsme’ export default class App extends Component { logSmiles(smiles) { console.log(smiles) } render () { return ( <div> <Jsme height="300px" width="400px" options="oldlook,star" onChange={this.logSmiles}/> </div> ) } } I have tried doing this by converting react component to the […]

Writing Clean Code in JavaScript

7 JavaScript clean coding tips every developer should know Writing clean code improves the maintainability of the application and make developers productive. However, some developers are unaware of the language features available to further enhance the code. In this article, I will discuss how we can utilize the features of JavaScript to write clean code. 1. Use Object […]

Problem with using setTimeout function together with an arrow function that sets a particular state

I am trying to replicate how when you hover over a particular movie tile on Netflix, after sometime the movie tile expands to display more information. Currently I have succeeded on expanding the tile to display more information on hover but setting a timeout such that the information is only displayed after the mouse has […]

Receive MAP in a string variable

I was wondering how set the variable list as String. const emails = [ {"ID": "11109", "VALUE": "[email protected]", "TYPE_ID": "EMAIL"}, {"ID": "13429", "VALUE": "[email protected]", "TYPE_ID": "EMAIL"}]; const list = emails.map(VALUE => VALUE.VALUE) console.log(list) //desired result:: [email protected],[email protected] console.log(typeof list); //string Source: JavaSript – Stack Overflow

Transform string intro array using Arrow Function

I was wondering if is possible to transform a string into an array using Arrow Function: var str = ‘[email protected];[email protected],[email protected]’; var result = str.split(‘;’).map(e => e.split(‘,’)) //desired result: {VALUE: ‘[email protected]’}, // {VALUE: ‘[email protected]}, // {VALUE: ‘[email protected]’} Source: JavaSript – Stack Overflow

How to rewrite this.getAttribute in an Arrow function?

I have problems understanding how to rewrite this to an arrow function. I know I can not use this. in an arrow function but how do I rewrite the same without this.? function flipCard() { let cardId = this.getAttribute("data-id"); cardsChosen.push(cardArray[cardId].name); cardsChosenId.push(cardId); this.setAttribute("src", cardArray[cardId].img); if (cardsChosen.length === 2) { setTimeout(checkForMatch, 500); } } Source: JavaSript – […]

An Introduction to JavaScript Functions For Beginners

A function is a set of statements that perform a specific task. It is one of the fundamental building blocks of JavaScript. Read the full story Source: Hacker Noon – JavaScript

What is the difference between Arrow Functions and Regular Functions when used for Class methods? [duplicate]

When working with Javascript objects, there is a big difference between using Arrow Functions compared to Regular Functions when it comes to this. For instance using a regular function here will properly bind this: const person = { name: "Karen", age: 40, hi: function() { console.log("Hi " + this.name); } } person.hi() // "Hi Karen" […]

IE does not support arrow(=>) [duplicate]

this is my code: function LoadDate() { document.querySelectorAll(‘[display-date]’).forEach(el => el.innerHTML = getTheDate()); } It is not working on IE because of this arrow (el => ) as I understand from my last question .. how can I convert it to be supported in all browsers? Thanks for your time ^_^ Source: JavaSript – Stack Overflow

new Promise with set state receives an arrow function

I was going through a react code base where I see the Promise function calling setstate with 2 arguments, I cannot exactly decipher how exactly this is working, everywhere I have seen a setState being created having one object argumemnt, but here we have a resolve argument that gets a setstate with an object and […]

react return jsx from function

From the FilterBydescription component of the Render function, I try to return the jsx element. But instead of the jsx in UseAdvertisementsFilters I get undefined. Most likely the context is lost, but I don’t understand why. Help return the jsx from the function. const FilterBydescription = () => { const [findByDescription, bindFindByDescription, resetFindByDescription] = useInput(”) […]

why will .this keyword not work on arrow functions, but will if it’s not an arrow function? [duplicate]

I’m a complete beginner with Javascript, so maybe this is obvious, but I’ve noticed something a little wierd with arrow functions/methods and .this in objects. I’m doing free code camp, and they want me to replace .dog with .this to access the below object. Take a look: let dog = { name: "Spot", numLegs: 4, […]

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Senior Software Developer

Creator of @LzoMedia I am a backend software developer based in London who likes beautiful code and has an adherence to standards & love's open-source.