Is there some convention to divide the HSL color circle into degree ranges to define basic colors? For example, degrees 80-150 would be considered green, degrees 210-280 as blue, and so on. I’d like to automatically detect pixel’s color belonging to some “color-group” and found that HS…
How to make React Redux async action return a promise?
I have a redux action function that returns a promise. Inside that function body, there is another async function that returns a callback when it finished the call. Then I call this function in another place chaining it with .then() but when debugging it in the browser with breakpoints, the promise function e…
(React and Redux) Problem with adding items to the shopping cart
I am following a tutorial, where we are building a shopping cart, which is still unfinished, but I would like to solve this problem before continuing in the tutorial. The thing is, that when I try to add any item to the cart, the cart is still saying me, that my shopping cart is empty. You can notice in the
How to remove duplicates by property of an object in an array of objects and copy all properties of duplicates?
I delete all duplicates by the “sourceType” property of the object in the array of objects, but I cannot copy the “dataType” property from the duplicates to the original, please check what I’ expecting in at output and expected output output: expected output: Answer You need to g…
Forwarding props from parent to child component
I have 2 components list of posts and when clicking on link on post card i’m entering into post. I can’t access props.postDetails in child component. When I console log the props, I have {history: {…}, location: {…}, match: {…}, staticContext: undefined} only this without props.postDetails. Can so…
TypeError: Cannot read property ‘on’ of undefined – App.componentWillMount
I am making an app in javascript with firebase. The problem is with the property “on”. I cant seem to fix it. The problem in line 31. –>> this.database.on(‘child_added’, snap => { The error is –>> TypeError: Cannot read property ‘on’ of undefined.…
How can the output elements put in an array in javascript?
function main() { var increase = parseInt(readLine(), 10); var prices = [98.99, 15.2, 20, 1026]; //your code goes here for(var i=0;i
What is the difference between react: class vs function App()?
When I download a react project, my default in App.js is : function App() However, a lot of YouTube tutorials uses: class App extends React.Component { Is there a difference between the two? Is one …
TypeError when swapping object properties with destructuring assignment [duplicate]
This question already has answers here: ES6 Array destructuring weirdness (4 answers) What are the rules for JavaScript’s automatic semicolon insertion (ASI)? (7 answers) Closed 1 year ago. I am trying to swap two object values in JavaScript using the [] = [] method, but my below code fails with an erro…
Why do I need this. keyword to reference a variable with the same name?
Good evening, This is my first post on stack overflow. I’m a newbie in programming and I can do many things in C++ – a language I love. However, recently I’ve moved on to javascript with the mission of getting hired. I’m creating a snake game and I’m automatizing its moves. I jus…