Can someone explain to me why I can't iterate over the properties (edit: falsely wrote prototypes first) of a class without creating an instance of it? A stupid little example would be:
export class Animal {
name: string;
colour: string;
constructor(init: string[]) {
this.name = init[0];
this.color = init[1]
}
}
Now, somewhere else in the program (long before the first book is "created"), I would like to do this:
for (const key in Object.keys(Animal) {
// here I would expect to iterate over the keys 'name' and 'colour' so I can do something like:
console.log(Animal[key]);
}
I'm aware, that it's not possible (previous post here and also according to MDN). But I don't understand the provided explanations. Could you explain to me why this is the case?
And, as a follow-up, how would I handle such a situation? Should I create an external interface/type that I loop over? I would generally like to have a single place that "holds" my animal properties.
Because the properties of Animal are non-enumerable as can be seen in this example:
Object.getOwnPropertyDescriptors(Animal)
{
"length": {
"value": 1,
"writable": false,
"enumerable": false,
"configurable": true
},
"name": {
"value": "Animal",
"writable": false,
"enumerable": false,
"configurable": true
},
"prototype": {
"value": {},
"writable": false,
"enumerable": false,
"configurable": false
}
}
If you set the properties in the class to static they become enumerable. Alternatively you can iterate them this way:
for (const key in Object.getOwnPropertyDescriptors(Animal)) {
console.log(Animal[key]);
}