Property Allsettled Does Not Exist On Type Promiseconstructor Ts2339

Have you ever encountered the error message: "Property 'allsettled' does not exist on type 'PromiseConstructor'? Well, don't worry, you're not alone. This error often pops up when working with promises in TypeScript, causing confusion for many developers. But fear not, we're here to break it down for you and help you understand what's going on.

Let's start by explaining what this error means. When you see the message "Property 'allsettled' does not exist on type 'PromiseConstructor'", it's usually because you're trying to use the 'allsettled' method on a Promise constructor in TypeScript. The 'allsettled' method isn't actually a native method on the PromiseConstructor interface in TypeScript.

So, what's the solution? Well, luckily there's a way to work around this issue. One common approach is to extend the existing Promise interface in TypeScript to add a custom 'allsettled' method. This can be done by creating a new interface that extends the global Promise interface and adds the 'allsettled' method.

Here's an example of how you can achieve this:

interface CustomPromise extends Promise {
    allsettled(promises: Promise[]): PromiseSettledResult[];
}

// Implement the 'allsettled' method on the CustomPromise interface
CustomPromise.prototype.allsettled = function(promises) {
    return Promise.allSettled(promises);
};

In this code snippet, we define a new interface called CustomPromise that extends the global Promise interface and adds the 'allsettled' method. We then implement the 'allsettled' method on the CustomPromise interface by calling the native Promise.allSettled method.

By extending the Promise interface in this way, you can now use the 'allsettled' method on promises in TypeScript without running into the TS2339 error. This approach allows you to leverage the power of TypeScript's type system while still having access to additional promise methods like 'allsettled'.

It's important to note that extending native interfaces in TypeScript should be done judiciously and with caution to avoid conflicts or unexpected behavior. However, in cases where you need to add custom functionality or work around limitations in TypeScript's type definitions, extending interfaces can be a helpful tool.

In conclusion, the "Property 'allsettled' does not exist on type 'PromiseConstructor' TS2339" error can be resolved by extending the Promise interface in TypeScript to add a custom 'allsettled' method. By using this approach, you can overcome the limitations of TypeScript's type definitions and work with promises more effectively in your code. We hope this explanation has been helpful, and happy coding!