Defining extenders in typescript

[Mario Valle]

I'm using ko with great satisfaction for a few years. Now I have moved to typescript for my projects and ko is supported very well by "@types/knockout": "^3.4.67" types.

My problem is that I cannot correctly add a new extender. I tried to add the example from https://knockoutjs.com/documentation/extenders.html but tsc complained that "Property 'logChange' does not exist on type 'KnockoutExtenders'."

Instead, adding new bindingHandlers works correctly.

Seems that the interface KnockoutExtenders is missing something like [bindingHandler: string]: KnockoutBindingHandler; present in the KnockoutBindingHandlers interface.

Is it a bug or a feature?

Thanks!

mario

[jks...@jkshay.com]

Do you need to add a custom typings file?

Sent from my iPhone

On Mar 24, 2020, at 1:08 PM, Mario Valle <silicon...@gmail.com> wrote:



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[Murat Duisenbayev]

I found this on stackoverflow:

https://stackoverflow.com/a/15424710/5492547

ko.extenders seems to be of type KnockoutExtenders, which is like this in the typings file:

interface KnockoutExtenders {
    throttle(target: any, timeout: number): KnockoutComputed<any>;
    notify(target: any, notifyWhen: string): any;
    rateLimit(target: any, timeout: number): any;
    rateLimit(target: any, options: { timeout: number; method?: string; }): any;
    trackArrayChanges(target: any): any;
}

It seems that it contains definitions for basic extenders that KO has by default. And in order to add a new extender's definition there you need to extend the KnockoutExtenders interface:

interface KnockoutExtenders {
    logChange(target: any, option: any): KnockoutObservable<any>;
}
ko.extenders.logChange = function (target: KnockoutObservable<any>, option: any) {
    target.subscribe(function (newValue) {
        console.log(option + ": " + newValue);
    });
    return target;
};

Hope this helps! 

вт, 24 мар. 2020 г. в 18:07, Mario Valle <silicon...@gmail.com>:

[Mario Valle]

Thanks! But I tried, and nothing changed. I don't understand why I cannot convince typescript to merge interface definitions if one is from node_modules @types and the other is local. Does this works for you?

mario

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[Murat Duisenbayev]

It seems to be working for me.

What exactly is being the obstacle while trying to use this method? What is the error message you are getting