There seems to be an issue with the TypeScript compiler indicating that the property "forEach" is not found in

Question

There seems to be an issue with the TypeScript compiler indicating that the property "forEach" is not found in

Hey, I've got an interesting situation with my Typescript interface:

interface sprite_loading {
[index: number]: {
    URL: string,
    name: string
}}

So, within the class, I'm creating an array like this:

public spriteLoading: sprite_loading;

However, when I attempt to iterate through this array using forEach:

private preload() {
    var phaser = this;
    this.spriteLoading.forEach(function (element) { //this is where things get tricky
        phaser.game.load.image(element.name, element.URL);
    });

}

Although the code functions correctly, I encounter this error message:

engine.ts:57:28 - error TS2339: Property 'forEach' does not exist on type 'sprite_loading'.

Can you believe it? Why am I getting this error if spriteLoading is indeed supposed to be an array?

typescript

Answer 1

Answer №1

Discovering the definition of an array comes effortlessly if you rely on it. For instance:

interface data_display extends Array<{ id: number, value: string}> {
    [index: number]: {
        id: number,
        value: string
    }
}

let example: data_display = [
    { id: 1, value: 'example' },
    { id: 2, value: 'sample' },
    { id: 3, value: 'test' }
];

example.forEach((val) => console.log(val.id));

If you prefer a more organized approach for your data_display interface, defining the type of each entry could be advantageous:

type Data = { id: number, value: string, items: Item[] };

let example: data_display = [
    { id: 1, value: 'example' },
    { id: 2, value: 'sample' },
    { id: 3, value: 'test' }
];

This method is also efficient for defining additional array members:

type Item = { attribute: number };
type Data = { id: number, value: string, items: Item[] };

let example: Data[] = [
    { id: 1, value: 'example', items: [{ attribute: 5 }, { attribute: 8 }] },
    { id: 2, value: 'sample', items: [] },
    { id: 3, value: 'test', items: [] }
];

example.forEach((val) => console.log(val.id));

Answer 2

Discovering the definition of an array comes effortlessly if you rely on it. For instance:

interface data_display extends Array<{ id: number, value: string}> {
    [index: number]: {
        id: number,
        value: string
    }
}

let example: data_display = [
    { id: 1, value: 'example' },
    { id: 2, value: 'sample' },
    { id: 3, value: 'test' }
];

example.forEach((val) => console.log(val.id));

If you prefer a more organized approach for your data_display interface, defining the type of each entry could be advantageous:

type Data = { id: number, value: string, items: Item[] };

let example: data_display = [
    { id: 1, value: 'example' },
    { id: 2, value: 'sample' },
    { id: 3, value: 'test' }
];

This method is also efficient for defining additional array members:

type Item = { attribute: number };
type Data = { id: number, value: string, items: Item[] };

let example: Data[] = [
    { id: 1, value: 'example', items: [{ attribute: 5 }, { attribute: 8 }] },
    { id: 2, value: 'sample', items: [] },
    { id: 3, value: 'test', items: [] }
];

example.forEach((val) => console.log(val.id));

There seems to be an issue with the TypeScript compiler indicating that the property "forEach" is not found in

Answer №1

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