Does nodejs requires bind class method? - node.js

Question

I am using node 12 in my project. Back to 2 years ago, I remember I need to bind method for class instance method like below:
class Logger {
constructor () {
this.printName = this.printName.bind(this);
}
printName (name = 'there') {
this.print(`Hello ${name}`);
}
print (text) {
console.log(text);
}
}
But recently I found I don't need to call bind in the constructor. Does the latest node version support auto-bind already?

Answer 1

The behavior hasn't changed. The situation in which you need to .bind is when the instance's printName method would otherwise get called without a calling context. For example:
class Logger {
printName (name = 'there') {
this.print(`Hello ${name}`);
}
print (text) {
console.log(text);
}
}
const l = new Logger();
const fn = l.printName;
fn();
or with, instead of fn:
setTimeout(l.printName)
or with:
button.addEventListener('click', l.printName)`
In all of these situations, an error will be thrown if you don't use .bind, because the method gets called without a calling context - but the calling context of the Logger instance is needed for this to refer to the instance, so that this.print refers to the print method of the instance.
This sort of thing has always been true in Javascript. Nothing's changed in the past few years, except that it's now a bit easier to bind - you can use new class field syntax instead of having a constructor:
class Logger {
printName = (name = 'there') => {
this.print(`Hello ${name}`);
}
print (text) {
console.log(text);
}
}
const l = new Logger();
const fn = l.printName;
fn();