is it possible to clone idiomatically a javascript class instance from within of its own method? Others languages like Java allow me to overwrite/clone the current instance by either construct overload or this overwrite. Javascript does not seems to like it, and throws the error SyntaxError: Invalid left-hand side in assignment. THere is an example below for this verbose explanation.
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
renew() {
this = new Car('Ferrari', 2021);
return this
}
}
car = new Car('Ford', 206)
car.renew()this can't be assigned to. For what you want, you must either:
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
renew() {
return new Car('Ferrari', 2021);
}
}
let car = new Car('Ford', 206)
car = car.renew()
console.log(car.year);class Car {
constructor(name, year) {
this.name = name;
this.year = year;
}
renew() {
Object.assign(this, new Car('Ferrari', 2021));
}
}
let car = new Car('Ford', 206)
car.renew()
console.log(car.year);No, it is not possible to do this. this is immutable. Your options would either be to modify the properties of the class, or create a new class instance and assign it to a your variable in enclosing scope.
I'm also not sure what language you are using that allows assignment to a this reference. It's not possible in Java, C#, Scala, or Ruby. It's technically possible in Python, but doesn't have the semantics you describe (e.g. it does not mutate the object). You can't even do it in C++.