@stdlib/iter-constant NPM

iterConstant

Create an iterator which always returns the same value.

Installation

npm install @stdlib/iter-constant

Usage

var iterConstant = require( '@stdlib/iter-constant' );

iterConstant( value[, options] )

Returns an iterator which always returns the same value.

var it = iterConstant( 3.14 );
// returns <Object>

var v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

// ...

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.

The function supports the following options:

iter: number of iterations. Default: 1e308.

By default, the function returns an infinite iterator (i.e., an iterator which never ends). To limit the number of iterations, set the iter option.

var opts = {
    'iter': 2
};
var it = iterConstant( 3.14, opts );
// returns <Object>

var v = it.next().value;
// returns 3.14

v = it.next().value;
// returns 3.14

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

Notes

When provided an object reference, the returned iterator always returns the same reference.

var arr = [ 1, 2, 3, 4 ];

var it = iterConstant( arr );
// returns <Object>

var v1 = it.next().value;
// returns [ 1, 2, 3, 4 ]

var bool = ( v1 === arr );
// returns true

var v2 = it.next().value;
// returns [ 1, 2, 3, 4 ]

bool = ( v2 === arr );
// returns true

// ...

To avoid unwanted object mutation, copy a provided value before creating an iterator.

If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var randu = require( '@stdlib/random-base-randu' );
var iterConstant = require( '@stdlib/iter-constant' );

// Create an iterator:
var opts = {
    'iter': 10
};
var it = iterConstant( randu(), opts );

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

Notice

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.