I assume that an ES6 class is an object as “everything” is objects in JavaScript. Is that a correct assumption? Answer From the point of view of Object Oriented Programming class is not an object. It is an abstraction. And every object of that is a concrete instance of that abstraction. From the p…
Tag: ecmascript-6
Javascript: Using `.includes` to find if an array of objects contains a specific object
I am a bit new to javascript ES6, and I am having difficulty understanding why the below is not functioning as expected: Thanks! Answer includes essentially checks if any element === the element you’re searching for. In case of objects, === means literally the same object, as in the same reference (same…
Are TemplateObject arrays for tagged template literals weakly referenced by their realm?
The JavaScript runtime creates a frozen array like Object.freeze([‘str0 ‘, ‘ str1’]) but with an additional .raw property. Is it okay to use that object as a key in a WeakMap to avoid having to redo work based on the array each time through the loop? Section 12.2.9.3 Runtime Semantics:…
How to flatten nested array of object using es6
I have this array of objects, within it I have another array of objects: How to get flat array of country like this: without using a forEach and a temp variable? When I did: I got the same structure back. Answer Latest edit All modern JS environments now support Array.prototype.flat and Array.prototype.flatMa…
Mock a dependency’s constructor Jest
I’m a newbie to Jest. I’ve managed to mock my own stuff, but seem to be stuck mocking a module. Specifically constructors. usage.js I’d like to do something like this in the tests. However when I come to use it in usage.js the cw is a mockConstructor not a FakeMetrics I realise that my appro…
Error is thrown but Jest’s `toThrow()` does not capture the error
Here is my error codes: As you can see the error did indeed occurred: Function FunctionThatDoesNotExistsInString does not exists in string.. However it is not captured as a pass in Jest. Here is my codes: Answer expect(fn).toThrow() expects a function fn that, when called, throws an exception. However you are…
Javascript – Template Strings Don’t Pretty Print Objects
Can I use ES6 template strings to pretty print javascript objects? This is from a React Native project, with console.log() outputting to Chrome debugging tools. What I Want outputs Template String Attempt outputs Question How do I get the first output (with the pretty printing) using template strings? Answer …
Export default was not found
I have a Vue 2 project, and I’ve written a simple function for translating months in dates, which I would like to import in one of my components, but I’m getting an error: export ‘default’ (imported as ‘translateDate’) was not found in ‘@/utils/date-translation’…
Merge arrays from object property in an object array [closed]
Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 5 years ago. Improve this question Give an array of objects as below: I would like to get an array of me…
How do I filter out a key from an object?
I have following object in JS. How can I select all keys except the first financial_year and put it into a new empty object? I understand I can do something like obj[“mainline_revenue”] to select individual elements but its a long list and I don’t want to type elements keys individually. New…