select.md

This is RxJS v 4. Find the latest version here

Rx.Observable.prototype.select(selector, [thisArg])

Rx.Observable.prototype.map(selector, [thisArg])

Ⓢ

Projects each element of an observable sequence into a new form by incorporating the element's index. There is an alias for this method called map.

Arguments

1. selector (Function | Object): Transform function to apply to each source element or an element to yield. If selector is a function, it is called with the following information:
   1. the value of the element
   2. the index of the element
   3. the Observable object being subscribed
2. [thisArg] (Any): Object to use as this when executing the predicate.

Returns

(Observable): An observable sequence which results from the comonadic bind operation.

Example

// Using a value
var md = Rx.Observable.fromEvent(document, 'mousedown').map(true);
var mu = Rx.Observable.fromEvent(document, 'mouseup').map(false);

// Using a function
var source = Rx.Observable.range(1, 3)
    .select(function (x, idx, obs) {
        return x * x;
    });

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

// => Next: 1
// => Next: 4
// => Next: 9
// => Completed

Location

File:

• /src/core/perf/operators/map.js

Dist:

• rx.all.js
• rx.all.compat.js
• rx.js
• rx.compat.js
• rx.lite.js
• rx.lite.compat.js

NPM Packages:

• rx

NuGet Packages:

• RxJS-All
• RxJS-Main
• RxJS-Lite

Unit Tests:

• /tests/observable/select.js