@stdlib/string-to-grapheme-cluster-iterator-right

graphemeClusters2iteratorRight

Create an iterator which iterates from right to left over grapheme clusters.

Installation

npm install @stdlib/string-to-grapheme-cluster-iterator-right

Usage

var graphemeClusters2iteratorRight = require( '@stdlib/string-to-grapheme-cluster-iterator-right' );

graphemeClusters2iteratorRight( src[, mapFcn[, thisArg]] )

Returns an iterator which iterates from right to left over each grapheme cluster in a string.

var iter = graphemeClusters2iteratorRight( '🌷🍕' );

var v = iter.next().value;
// returns '🍕'

v = iter.next().value;
// returns '🌷'

var bool = iter.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.

To invoke a function for each src value, provide a callback function.

function fcn( v ) {
    return v + v;
}

var it = graphemeClusters2iteratorRight( 'beep', fcn );
// returns <Object>

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

v = it.next().value;
// returns 'ee'

v = it.next().value;
// returns 'ee'

// ...

The invoked function is provided three arguments:

value: grapheme cluster.
index: iterated value index.
src: source string.

function fcn( v, i ) {
    return v + i;
}

var it = graphemeClusters2iteratorRight( 'bar', fcn );
// returns <Object>

var v = it.next().value;
// returns 'r2'

v = it.next().value;
// returns 'a1'

v = it.next().value;
// returns 'b0'

// ...

To set the callback function execution context, provide a thisArg.

function fcn( v ) {
    this.count += 1;
    return v;
}

var ctx = {
    'count': 0
};

var it = graphemeClusters2iteratorRight( '🌷🍕', fcn, ctx );
// returns <Object>

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

v = it.next().value;
// returns '🌷'

var count = ctx.count;
// returns 2

Notes

If an environment supports Symbol.iterator, the returned iterator is iterable.
In environments supporting Symbol.iterator, the function explicitly does not invoke a string's @@iterator method, regardless of whether this method is defined. To convert a string to an implementation defined iterator, invoke this method directly.

Examples

var graphemeClusters2iteratorRight = require( '@stdlib/string-to-grapheme-cluster-iterator-right' );

function repeat( str ) {
    return str + str;
}

// Create an iterator which iterates over grapheme clusters:
var it = graphemeClusters2iteratorRight( 'Iñtërnâtiônàlizætiøn', repeat );

// 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.