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 }

Most simplest approach would be this selectedCategory = categories.forEach(catApi => { if(catApi.id == requiredId) return catApi}) — Sumit Agarwal
– Sumit Agarwal, Commented Dec 7, 2016 at 5:08

Bazinga · Accepted Answer · 2016-12-07 10:21:41Z

23

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];

answered Dec 7, 2016 at 10:21

Bazinga

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slaesh · Accepted Answer · 2016-12-07 06:01:54Z

2

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:

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

answered Dec 7, 2016 at 6:01

slaesh

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