Having recently bitten by a mistyped property name (see code underneath
signature), I think I might prevent the extension of instances more often. But
what is the best way of doing so?
Variant 1: prevents subtyping the constructor
function Point(x, y) {
this.x = x;
this.y = y;
Object.seal(this);
}
Variant 2: allows subtyping, not very pretty.
function Point(x, y) {
this.x = x;
this.y = y;
if (Object.getPrototypeOf(this) === Point.prototype) {
Object.seal(this);
}
}
--
Dr. Axel Rauschmayer
[email protected]
home: rauschma.de
twitter: twitter.com/rauschma
blog: 2ality.com
Buggy code:
var action = function() { ... };
var c = new CountDown(1, action);
c.dec(); // action is *not* executed!
function CountDown(counter, finalAction) {
this.counter = counter;
this.finalAction = finalAction;
// Important! finalAction must always be executed
this.maybeFire();
}
CountDown.prototype.maybeFire = function () {
if (this.counter <= 0 && this.finalAction) {
this.finalAction();
}
};
CountDown.prototype.dec = function () {
this.conter--; // typo!
this.maybeFire();
};
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