Questions tagged [class-fields]
55 questions
15
votes
3 answers
What are "class fields" in JavaScript?
I was reading about JavaScript classes, and came across this term "public class fields syntax". On digging a bit deeper into it I came across this Babel's documentation on class properties.
Can someone please explain - implementation-wise what are…
Aaditya Sharma
- 3,330
- 3
- 24
- 36
15
votes
2 answers
What is the difference between class fields and properties in Javascript
I'm reading class fields proposal for JavaScript. I don't understand why the authors call it 'fields' and not properties.
MDN docs in class article speak about instance properties declared inside constructor and in next section about field…
bifi
- 175
- 1
- 7
14
votes
1 answer
Arrow vs classic method in ES6 class
Is there any reason to write classic syntax of ES6 methods?
class MyClass {
myMethod() {
this.myVariable++;
}
}
When I use myMethod() as callback on some event, I must write something like this (in JSX):
// Anonymous…
Vesmy
- 1,190
- 4
- 15
- 29
13
votes
1 answer
How to use private class fields in nodejs 12?
In the current release of nodejs i.e. 12.x.x, we can declare private class fields by the #some_varible notation. The # notation would make the variable private field for that particular class.
class Foo {
#some_varible = 10;
}
I have the…
Rajan Sharma
- 2,211
- 3
- 21
- 33
11
votes
6 answers
js dynamically access private fields (properties/members)
I'm trying out the new class private member feature However, I've quickly run into a problem: How does one dynamically access them?
I expected it to follow pre-existing syntax of either
constructor(prop, val) {
this[`#${prop}`] = val; //…
Jakob Jingleheimer
- 30,952
- 27
- 76
- 126
10
votes
2 answers
How to Enumerate Private JavaScript Class Fields
How do we enumerate through private class fields?
class Person {
#isFoo = true;
#isBar = false;
constructor(first, last) {
this.firstName = first;
this.lastName = last;
}
enumerateSelf() {
console.log(this);
// (pub/priv…
anthumchris
- 8,245
- 2
- 28
- 53
10
votes
3 answers
When using React Is it preferable to use fat arrow functions or bind functions in constructor?
When creating a React class, which is preferable?
export default class Foo extends React.Component {
constructor (props) {
super(props)
this.doSomething = this.doSomething.bind(this)
}
doSomething () { ... }
}
or
export default class…
davegri
- 2,206
- 2
- 26
- 45
8
votes
1 answer
Why are arrow functions as static members values not lexically scoped?
class Foo {
static v = 123;
static bar = () => this.v;
}
console.log(Foo.bar());
I expect this code to return undefined, because arrow functions are lexically scoped, hence this must be eagerly bound to the outer scope.
Yet, it returns…
zerkms
- 249,484
- 69
- 436
- 539
7
votes
1 answer
Access private members from developer console?
Before, I would use the old convention of naming fields intended to be private with an _ suffix or prefix.
class X{
constructor() {
this.privateField_;
}
privateMethod_() {}
}
Now that real private accessibility is possible with the #…
junvar
- 11,151
- 2
- 30
- 46
4
votes
3 answers
Private class field in JavaScript
class A {
#a = 1;
static #a = 2;
}
Results in
Uncaught SyntaxError: redeclaration of private name #a in Firefox
Uncaught SyntaxError: Identifier '#a' has already been declared in Chrome
While
class A {
a = 1;
static a = 2;
}
is valid in…
Carter Li
- 149
- 12
4
votes
1 answer
Accessing a class field on a superclass
I have a file with the following code:
class Animal {
doSomething = () => {
return 'Hi.';
};
}
class Dog extends Animal {
doSomething = () => {
return super.doSomething() + ' Woof!';
…
Elias Zamaria
- 96,623
- 33
- 114
- 148
4
votes
3 answers
What's difference between two ways of defining method on React Class in ES6
I see this a lot in ES6 React code
class Foo extends React.Component {
bar = () => {
console.log("bar")
}
baz() {
console.log("baz")
}
}
Seems like they both define methods bar and baz on Foo but how are they different.
User314159
- 7,733
- 9
- 39
- 63
4
votes
2 answers
ESLint shows error on class instance property initialized to arrow function
maybe similar to How do I configure ESLint to allow fat arrow class methods
When class method defined as arrow function Eslint highlight error 'method' is not defined. (no-undef).
simple example
class abc {
d = () => {
// method body
…
n06rin
- 173
- 2
- 9
3
votes
2 answers
Cannot read private member from an object whose class did not declare it...?
In this program:
class Example {
#privateMember = 123;
// these are fine
addNumber (n) { return this.#privateMember + n; }
doAddNumber (n) { return this.addNumber(n); }
// "cannot read private member #privateMember from an
//…
Jason C
- 38,729
- 14
- 126
- 182
3
votes
1 answer
Unexpected token "=" reported while running eslint on arrow functions
I have a JavaScript class and inside it I have an async method which looks like below.
class ABC {
func = async () => { //----line 10
//some code
}
func2 = () => { //----line 11
//some code
}
}
When I run ESLint…
Naxi
- 1,504
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- 72