There seems something inherently wrong with having to define a Promise’s callback as asynchronous: This is apparently an antipattern and there are coding problems which can arise from it. I understand that it becomes easier to fail to catch errors here, even when placing await statements inside try/catch blocks. My first question is, what’s the best way to code something
Tag: ecmascript-6
Unable to display Date in JSX in ReactJS
Following is my code which is working fine if I initialize test with a string, though if I changed it to new Date() its throwing error. Let me know what I am doing wrong as I just started with React. Code – Error – Objects are not valid as a React child (found: Fri Jul 21 2017 02:11:18 GMT+0530 (India
How to properly use Object.setPrototypeOf()
So I’ve been getting up to speed on some of the newer features of JavaScript and have been reading about Object.setPrototypeOf(). I ran across this bit of code from MDN which deals with inheriting from regular objects. But I’m confused at how they use Object.setPrototypeOf() here. I expected them to write as opposed to what the do below. Why do
Programmatically cause onBlur to trigger in react
I use onBlur to close a dropdown, but I also want to handle a click handler of an li which is render within, setState won’t work here, the behavior is broken when user try to open the dropdown again, try it here: http://jsfiddle.net/ur1rbcrz My code: Answer Your code is not working because, even though you click li, a div container
ReactJS “Unhandled Rejection (TypeError): this.state.features.map is not a function”
I’m learning React and now I’m trying to do a get request and list with map but when I run this code they come up with this error “Unhandled Rejection (TypeError): this.state.features.map is not a function”. I have already searched this but I do not understand what is going on. Answer In your componentWillMount, just do this: The response you
Enums in Javascript with ES6
I’m rebuilding an old Java project in Javascript, and realized that there’s no good way to do enums in JS. The best I can come up with is: The const keeps Colors from being reassigned, and freezing it prevents mutating the keys and values. I’m using Symbols so that Colors.RED is not equal to 0, or anything else besides itself.
ES6 – is there an elegant way to import all named exports but not the default export?
I am looking for an elegant way to import all named exports without having to import the default as well. In one file I am exporting many named constants plus a default: In another file I would like to have an elegant way to import all named exports only, without having to import the default: I do not want to:
Jest equivalent to RSpec lazy evaluated variables (let)?
In rspec you can do something like this: This allows you to define a method call or instantiation of a large object as a sum of its smaller parts. You can then override those individual small parts inside different contexts. The idea being that you create a happy path before each test, and then specify deviations from the happy path
Update one of the objects in array, in an immutable way
In React’s this.state I have a property called formErrors containing the following dynamic array of objects. Let’s say I would need to update state’s object having the fieldName cityId to the valid value of true. What’s the easiest or most common way to solve this? I’m OK to use any of the libraries immutability-helper, immutable-js etc or ES6. I’ve tried
Why would you try-catch around a promise? Does that catch the promise’s error?
I stumbled upon some code that looked off to me: If some somePromise() fails, would this not get caught, and the app would crash? Does this try-catch even do anything? Should be this, correct?: Answer TL;DR – If a function that returns a promise throws an exception before returning the promise then that exception would have to be caught in