elementatordefault.md

Rx.Observable.prototype.elementAtOrDefault(index, [defaultValue])

Ⓢ

Returns the element at a specified index in a sequence.

Arguments

1. index (Number): The zero-based index of the element to retrieve.
2. [defaultValue = null] (Any): The default value if the index is outside the bounds of the source sequence.

Returns

(Observable): An observable sequence that produces the element at the specified position in the source sequence, or a default value if the index is outside the bounds of the source sequence.

Example

/* Finds an index */
var source = Rx.Observable.fromArray([1,2,3,4])
    .elementAt(1);

var subscription = source.subscribe(
    function (x) {
        console.log('Next: ' + x);
    },
    function (err) {
        console.log('Error: ' + err);   
    },
    function () {
        console.log('Completed');   
    });

// => Next: 2
// => Completed 

/* Not found */
var source = Rx.Observable.fromArray([1,2,3,4])
    .elementAt(4, 0);

var subscription = source.subscribe(
    function (x) {
        console.log('Next: ' + x);
    },
    function (err) {
        console.log('Error: ' + err);   
    },
    function () {
        console.log('Completed');   
    });

// => Next: 0
// => Completed 

Location

File:

• /src/core/linq/observable/elementatordefault.js

Dist:

• rx.all.js
• rx.all.compat.js
• rx.aggregates.js

Prerequisites:

• rx.js | rx.compat.js | rx.lite.js | rx.lite.compat.js

NPM Packages:

• rx

NuGet Packages:

• RxJS-All
• RxJS-Aggregates

Unit Tests:

• /tests/observable/elementatordefault.js