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 point of view of JavaScript, class is
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 place in memory), not the same shape. But
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: GetTemplateObject ( templateLiteral ) describes how this value is cached:
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.flatMap Old answer No need for any ES6 magic,
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 approach might be ‘less than idiomatic’
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 calling CheckFunctionExistenceByStr immediatelly, which causes the function to throw before
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 Your first example does not actually output a string to the
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’ The relative file path from the src folder is correct, and I am exporting the function like
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 merged items from fields property and
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 object would look like this: Answer You could just