I have this interface

export interface IFilaActividad {
 [key: string]: any
}

And I create properties in it dynamically

var filaActividad: IFilaActividad = {}

this.columnsToDisplay.forEach(c => {
  Object.defineProperty(filaActividad, c, {});
}
);

I see my properties and now I want to log them

for (let prop in filaActividad) {
  console.log("Propiedades", prop);
}

But nothing is logged, never pass inside the for

Any idea, please?

Thanks

CodePudding user response：

By default, properties added using Object.defineProperty() are not writable, not enumerable, and not configurable!

When you define a property this way, you can't overwrite it, delete or access via for...in or Object.keys by default! In order to make it possible to do so, you need to provide additional flags to the third parameter, the data descriptor object.

Insead of

Object.defineProperty(filaActividad, c, {});

... you should ...

Object.defineProperty(filaActividad, c, {
    configurable: true,
    writable: true,
    enumerable: true,
    value: undefined
});

Source

CodePudding user response：

You don't see anything because all the values within your object are undefined (based on the image posted).

If you want to see the keys of your object, then just log the prop:

for (let prop in filaActividad) {
  console.log("key", prop);
  console.log("the value of that prop: ", filaActividad[prop])
}

If you only interested in your object keys, you could also use Object.keys:

const myKeys = Object.keys(filaActividad); // string[]

for (const key of myKeys) {
  console.log("key : ", key);
}