Twifty :
Since es6 doesn't support nested classes, I've taken to adding a nested class to a static getter of the parent. For example:
class Dictionary {
static get Category () {
return class Category {
static is (inst) {
return inst instanceof Category
}
constructor () {}
}
}
}
However, I'm having a problem with instanceof. I want to make sure a given variable is a correct instance.
const test = new Dictionary.Category()
const ctor = Dictionary.Category
console.log(test instanceof Dictionary.Category) // false
console.log(Dictionary.Category.is(test)) // false
console.log(test instanceof ctor) // false
console.log(test.__proto__.constructor === ctor) // false
console.log(test.constructor === ctor) // false
console.log(test.constructor, ctor) // both function Category()
console.log(new Dictionary() instanceof Dictionary) // true (sanity check)
Up till now, I've been testing the constructor.name but this is limited. How can I solve this problem?
Thanks to the answer below pointing out the problem, here is a working solution:
class Dictionary {
static get Category () {
Dictionary.__Category = Dictionary.__Category || class Category {
constructor () {}
}
return Dictionary.__Category
}
}
loganfsmyth :
This is failing because every access of the getter property creates a whole new class, it just happens to have all the same stuff as the one you got last time you accessed the getter.
If you want a nested property, use a property, e.g.
class Dictionary {
}
Dictionary.Category = class Category {
static is (inst) {
return inst instanceof Category
}
constructor () {}
};
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