everybody knows that arrow functions inside methods forget their 'this'.
Does everybody else know how to work around that? Does `bind()` do
something helpful?

--
lazy amateur

luserdroog:

> everybody knows that arrow functions inside methods forget their 'this'.
> Does everybody else know how to work around that? Does `bind()` do
> something helpful?

<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions>

--
Arno Welzel
https://arnowelzel.de

Le 25/03/2022 à 05:57, luserdroog a écrit :
> everybody knows that arrow functions inside methods forget their 'this'.
> Does everybody else know how to work around that? Does `bind()` do
> something helpful?
>

Don't know what you mean...

class Test {

constructor(name) {
this.name = name;
}

getName(delay) {
setTimeout(
() => {
console.log(this.name);
}, delay);
}
}

const t1 = new Test("test 1");
const t2 = new Test("test 2");

t1.getName(500);
t2.getName(100);
->
test 2
test 1

anonymous arrow function inherits this from the function where it is
defined (the getName method) whose this is the test object.
of course

const f = t1.getName;
f(100);
->
D:\xxxxxxxxxxxxxxxxxxxxxxx\test.js:10
console.log(this.name);
TypeError: Cannot read properties of undefined (reading 'name')

the call to method getName via f(100) make this to be undefined so is
this for arrow function

and

const f = t1.getName.bind(t1);
f(100);
->
test 1

On Thursday, March 24, 2022 at 11:57:28 PM UTC-5, luser...@gmail.com wrote:
> everybody knows that arrow functions inside methods forget their 'this'.
> Does everybody else know how to work around that? Does `bind()` do
> something helpful?

You use a function instead of a lambda. This is by design.

The alternative is to pass 'this' as an explicit argument:

(self, foo) => {...}

On Thu, 24 Mar 2022 21:57:24 -0700 (PDT), luserdroog wrote:
> everybody knows that arrow functions inside methods forget their 'this'.
> Does everybody else know how to work around that? Does `bind()` do
> something helpful?

Arrow function is not a replacement or a "better" version of the normal
function. Both have different purposes.