Steps for incorporating a custom Knockout function in Typescript

Question

Steps for incorporating a custom Knockout function in Typescript

I need to create an event binding for my observable array in order to trigger a function when the input (e.g., description) changes. I've looked at various solutions online but none of them seem to be working with Typescript. Below is the code I have:

HTML:

<tbody data-bind="foreach: income">
<tr>
<td><input data-bind="value: description, event: {change: save} "/></td>
<td><input data-bind="value: amount"/></td>
</tr>
</tbody>

Typescript:

ko.observableArray.fn['save'] = function () {
  // does something
}
income = ko.observableArray([{ description: 'Description', amount: '0'}]);
this.addIncome.save();

The error message states that Property 'saveExtendedBalance' does not exist on type 'KnockoutObservableArray'. How can I rephrase this code?

javascript knockout.js

Answer 1

Answer №1

It seems like you're having trouble declaring your knockout observable array. If you want to initialize the array with at least one object, you'll need to make a small change in the code:

income = ko.observableArray({ description: 'Description', amount: '0'});

You should update it to look like this:

income = ko.observableArray([{ description: 'Description', amount: '0'}]);

The reason for this adjustment is that you need to treat the income variable as an array instead of an object when initializing it.

Answer 2

It seems like you're having trouble declaring your knockout observable array. If you want to initialize the array with at least one object, you'll need to make a small change in the code:

income = ko.observableArray({ description: 'Description', amount: '0'});

You should update it to look like this:

income = ko.observableArray([{ description: 'Description', amount: '0'}]);

The reason for this adjustment is that you need to treat the income variable as an array instead of an object when initializing it.

Answer 3

Answer №2

Here is a detailed example that meets your requirements:

I have also created a function to remove elements from the array for your convenience.

Below is the TypeScript code provided:

class CustomExample {
    customArray: KnockoutObservableArray<string> = ko.observableArray([]);
    customToAdd: KnockoutObservable<string> = ko.observable("");

    addElement = ():void => this.customArray.push(this.customToAdd());

    removeElement = (elementToRemove: string):string[] => this.customArray.remove(elementToRemove);
}

ko.applyBindings(new CustomExample(), document.getElementById("Custom"));

And here is the corresponding HTML code:

<section id="custom">
    <input type="text" data-bind="value: customToAdd, event: {change: addElement}">
    <h3 data-bind="visible: customArray().length > 0">Your array:</h3>
    <ul data-bind="foreach: customArray">
        <li><span data-bind="text: $data"></span> - <button data-bind="click: $parent.removeElement">Remove Element</button></li>
    </ul>
</section>

Please note that the dependencies include "@types/knockout": "^3.4.38".

Answer 4

Here is a detailed example that meets your requirements:

I have also created a function to remove elements from the array for your convenience.

Below is the TypeScript code provided:

class CustomExample {
    customArray: KnockoutObservableArray<string> = ko.observableArray([]);
    customToAdd: KnockoutObservable<string> = ko.observable("");

    addElement = ():void => this.customArray.push(this.customToAdd());

    removeElement = (elementToRemove: string):string[] => this.customArray.remove(elementToRemove);
}

ko.applyBindings(new CustomExample(), document.getElementById("Custom"));

And here is the corresponding HTML code:

<section id="custom">
    <input type="text" data-bind="value: customToAdd, event: {change: addElement}">
    <h3 data-bind="visible: customArray().length > 0">Your array:</h3>
    <ul data-bind="foreach: customArray">
        <li><span data-bind="text: $data"></span> - <button data-bind="click: $parent.removeElement">Remove Element</button></li>
    </ul>
</section>

Please note that the dependencies include "@types/knockout": "^3.4.38".

Steps for incorporating a custom Knockout function in Typescript

Answer №1

Answer №2

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