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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

iterPop

NPM version Build Status Coverage Status

Create an iterator which skips the last value of a provided iterator.

Usage

import iterPop from 'https://cdn.jsdelivr.net/gh/stdlib-js/iter-pop@esm/index.mjs';

iterPop( iterator[, clbk[, thisArg]] )

Returns an iterator which skips the last value of a provided iterator.

import array2iterator from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-to-iterator@esm/index.mjs';

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

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

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

v = it.next().value;
// returns 3

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.

To invoke a callback upon skipping the last value of a provided iterator, provide a clbk argument.

import array2iterator from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-to-iterator@esm/index.mjs';

function onPop( v ) {
    console.log( v );
    // => 4
}

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

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

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

v = it.next().value;
// returns 3

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

The callback function is provided a single argument:

  • v: the skipped value

To set the callback execution context, provide a thisArg.

import array2iterator from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-to-iterator@esm/index.mjs';

function onPop() {
    this.count += 1;
}

var ctx = {
    'count': 0
};

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

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

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

v = it.next().value;
// returns 3

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

bool = ( ctx.count === 1 );
// returns true

Notes

  • If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import randu from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-iter-randu@esm/index.mjs';
import iterPop from 'https://cdn.jsdelivr.net/gh/stdlib-js/iter-pop@esm/index.mjs';

// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
    'seed': 1234,
    'iter': 10
});

// Create an iterator which skips the last number:
var it = iterPop( rand );

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

</script>
</body>
</html>

See Also

  • @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.
  • @stdlib/iter-slice: create an iterator which returns a subsequence of iterated values from a provided iterator.

Notice

This package is part of stdlib, a standard library 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.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.