@stdlib/iter-pop
v0.2.2
Published
Create an iterator which skips the last value of a provided iterator.
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iterPop
Create an iterator which skips the last value of a provided iterator.
Installation
npm install @stdlib/iter-pop
Usage
var iterPop = require( '@stdlib/iter-pop' );
iterPop( iterator[, clbk[, thisArg]] )
Returns an iterator which skips the last value of a provided iterator
.
var array2iterator = require( '@stdlib/array-to-iterator' );
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 adone
property having aboolean
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.
var array2iterator = require( '@stdlib/array-to-iterator' );
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
.
var array2iterator = require( '@stdlib/array-to-iterator' );
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
var randu = require( '@stdlib/random-iter-randu' );
var iterPop = require( '@stdlib/iter-pop' );
// 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 );
}
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 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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.