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JavaScript Defining static fields with conditions in a class

I want to create code(example) like this:

class foo {
    static [x % 2 == 0]() {
        return x / 2;
    }
    static [x % 2 == 1]() {
        return x * 3 + 1;
    }
}

I tried many ways but it didn’t work.

Is it possible to get the key value used to access a field in JavaScript?
Or is it possible to give default values ​​to undefined fields?

class foo {
    static a = 1;
    static b = 2;
    static default(x) = 6 + x;
}
> foo.a -> 1
> foo.b -> 2
> foo.c -> "6c"
> foo.d -> "6d"
... and so on
Tags:

2

Answers


  1. 0

    In JavaScript, the syntax you provided isn’t valid because you cannot directly define class fields or methods with dynamic names or conditional logic in the way you are attempting.

    class Foo {
    static calculate(x) {
        if (x % 2 === 0) {
            return x / 2;
        } else {
            return x * 3 + 1;
        }
    }
}
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  2. 0

    Consider using Proxy:

    class Foo {
  static a = 1;
  static b = 2;
}

const foo = new Proxy(Foo, {
  get(target, prop) {
    if (typeof target[prop] === 'undefined') {
      return '6' + prop;
    }
    return target[prop];
  },
});

console.log(foo.a);
console.log(foo.b);
console.log(foo.c);
console.log(foo.d);
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