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Create an iterator which prepends values to the beginning of a provided iterator.
npm install @stdlib/iter-unshiftAlternatively,
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scripttag without installation and bundlers, use the ES Module available on theesmbranch (see README). - If you are using Deno, visit the
denobranch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umdbranch (see README).
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To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
var iterUnshift = require( '@stdlib/iter-unshift' );Returns an iterator which prepends values to the beginning of a provided iterator.
var array2iterator = require( '@stdlib/array-to-iterator' );
var it = iterUnshift( array2iterator( [ 1, 2 ] ), 3, 4 );
// returns <Object>
var v = it.next().value;
// returns 3
v = it.next().value;
// returns 4
v = it.next().value;
// returns 1
v = it.next().value;
// returns 2
var bool = it.next().done;
// returns trueThe 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
valueproperty and adoneproperty having abooleanvalue indicating whether the iterator is finished. - return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.
var randu = require( '@stdlib/random-iter-randu' );
var iterUnshift = require( '@stdlib/iter-unshift' );
// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234,
'iter': 10
});
// Create an iterator with prepended values:
var it = iterUnshift( rand, 'beep', 'boop' );
// Perform manual iteration...
var v;
while ( true ) {
v = it.next();
if ( v.done ) {
break;
}
console.log( v.value );
}@stdlib/iter-concat: create an iterator which iterates over the values of two or more iterators.@stdlib/iter-push: create an iterator which appends additional values to the end of a provided iterator.@stdlib/iter-shift: create an iterator which skips the first value of a provided iterator.
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
Copyright © 2016-2024. The Stdlib Authors.
