iterHead

Create an iterator which returns the first n values of a provided iterator.

Usage

var iterHead = require( '@stdlib/iter/head' );

iterHead( iterator, n )

Returns an iterator which returns the first n values of a provided iterator.

var array2iterator = require( '@stdlib/array/to-iterator' );

var it = iterHead( array2iterator( [ 1, 2, 3, 4 ] ), 2 );
// returns <Object>

var v = it.next().value;
// returns 1

v = it.next().value;
// returns 2

var bool = it.next().done;
// returns true

The returned iterator protocol-compliant object has the following properties:

  • next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
  • return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

Notes

  • If a provided iterator only generates m values and m is less than n, the returned iterator only returns m values.
  • If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

var randu = require( '@stdlib/random/iter/randu' );
var iterHead = require( '@stdlib/iter/head' );

var rand;
var it;
var r;

// Create a seeded iterator for generating pseudorandom numbers:
rand = randu({
    'seed': 1234
});

// Create an iterator which returns the first 10 generated numbers:
it = iterHead( rand, 10 );

// Perform manual iteration...
while ( true ) {
    r = it.next();
    if ( r.done ) {
        break;
    }
    console.log( r.value );
}