How can I write the following code in TypeScript without getting an error from the compiler?
if(navigator.share)
{
navigator.share(...);
}
The specific error message is: Property share is not found in navigator.
It's worth noting that Navigator.share is a function that some browsers have while others don't. Is there a way to adjust my TypeScript code so that the compiler doesn't throw an error, while still performing the necessary check?
If you want to implement it, follow these steps:
if (navigator['share']) {
const share = navigator['share'];
share();
console.log(navigator['share']);
}
@cyrix continues to argue that this code will result in a compiler error. It won't. Check out this screenshot showing the code in action
There are various ways to determine if a property exists on an object:
1. To check if an object owns a property, you can use:
if(car.hasOwnProperty('model')) {
// ...
}
2. If you want to confirm if a property is part of the object's prototype, you can utilize:
if(Object.getPrototypeOf(car).hasOwnProperty('model')) {
// ...
}
Note:
car.__proto__.hasOwnPropertycould also work, but it's only consistent since the ECMAScript2015 spec.
3. To verify if a property exists on an object, you can use:
if(car['model']) {
// ...
}
You should also ensure to check its type as typeof Function before invoking it.
In your particular case, if model is part of the Car.prototype, the second option would be suitable. Additionally, you need to inform TypeScript that the car has the model method because car['model']() will fail if the noImplicitAny option is enabled.
if (Object.getPrototypeOf(car).hasOwnProperty('model')) {
if(typeof (car as Car & { model: Function }).model === typeof Function) {
(car as Car & { model: Function }).model()
}
}
For the TypeScript compiler, the
(car as Car & { model: Function }).model()Alternatively, you could define your own global type for the experimental Car.model method:
type ExperimentalCarModel = (details:
{ brand: string, year?: number, color?: string }
| { brand?: string, year: number, color?: string }
| { brand?: string, year?: number, color: string }
) => void;
declare type ExperimentalCar = Car & {
model: ExperimentalCarModel
}
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