Typescript Array find element by index

Question

Finding and assigning a CategoryApi object having categoryId

export class CategoryApi {
    categoryId: number;
    name: string;
}

categories: CategoryApi[];
selectedCategory: CategoryApi;

selectedCategory = categories.findByIndex(2); //looking for categoryApi by categoryId = 2

I found this javascript option but Typescript is complaining about function

var inventory = [
    {name: 'apples', quantity: 2},
    {name: 'bananas', quantity: 0},
    {name: 'cherries', quantity: 5}
];

function findCherries(fruit) { 
    return fruit.name === 'cherries';
}

console.log(inventory.find(findCherries)); // { name: 'cherries', quantity: 5 }

Answer 1

There is no such method findByIndex in JS, the only method is findIndex.

You can use the filter or the find method to get the item by index:

// ES2015

selectedCategory = categories.find(item => item.categoryId === 1);

// ES5

selectedCategory = categories.filter(item => item.categoryId === 1)[0];

Answer 2

TO get specific parameter values. Use this code

this.categories.find(item => item.categoryId === 1).categoryId 

WHere categoryId can be any field you want

Answer 3

You can use the find method:

selectedCategory = categories.find(c => c.categoryApi == 2);

The problem is, that the find function isn't listed in the typings-file.

First, ignore the error-message and try it!

Second, you could edit the typings-file:

1. change find with filter and press F12 (go to declaration)
2. copy this line in the typings-file and rename the function to find and the returned value to single-object instead of an array!
3. save that file
4. rename your back filter to find in your code..