Exploring the world of Typescript and Angular Filter functionalities

Question

Exploring the world of Typescript and Angular Filter functionalities

I am looking to utilize one of my Angular Filters in my controller as a function. I came across a solution on this page: How to use a filter in a controler

The last answer provided exactly what I needed, so I implemented it in my JS code:

    var MyFunc = $filter('MyGreatFilter');
    var resp = MyFunc(6);

It worked perfectly fine. However, I am using Typescript and struggling to assign the correct type to it. Without any type, I encounter the following error:

error TS2349: Cannot evoke an expression whose type lacks a call signature

When I include this type in my controller's interface:

MyFunc(val:number): string;

I get an error that is confusing to me:

error TS2322: Type {} is not assignable to type '(val: number) => string'

The function takes a number as input and returns a string. Any suggestions on how to properly type the Filter function MyFunc?

Thank you.

javascript angularjs typescript

Answer 1

Answer №1

After some exploration, I stumbled upon the solution tucked away in another section of code that was authored by a much more ingenious individual. To implement this filter, you'll need to define a Typescript interface above it:

interface IFilterMyGreatFilterName {
(value: number): string;
}

function MyGreatFilter () {
    return function (item:number) {
        // Apply filtering logic and return a string
    };
}

Next, make sure to invoke the function in a slightly different manner from what was demonstrated earlier:

var resp = $filter<IFilterMyGreatFilterName>('MyGreatFilter')(aNumValue);

Answer 2

After some exploration, I stumbled upon the solution tucked away in another section of code that was authored by a much more ingenious individual. To implement this filter, you'll need to define a Typescript interface above it:

interface IFilterMyGreatFilterName {
(value: number): string;
}

function MyGreatFilter () {
    return function (item:number) {
        // Apply filtering logic and return a string
    };
}

Next, make sure to invoke the function in a slightly different manner from what was demonstrated earlier:

var resp = $filter<IFilterMyGreatFilterName>('MyGreatFilter')(aNumValue);

Exploring the world of Typescript and Angular Filter functionalities

Answer №1

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