# iterPop > Create an [iterator][mdn-iterator-protocol] which skips the last value of a provided [iterator][mdn-iterator-protocol].
## Usage ```javascript var iterPop = require( '@stdlib/iter/pop' ); ``` #### iterPop( iterator\[, clbk\[, thisArg]] ) Returns an [iterator][mdn-iterator-protocol] which skips the last value of a provided [`iterator`][mdn-iterator-protocol]. ```javascript var array2iterator = require( '@stdlib/array/to-iterator' ); var it = iterPop( array2iterator( [ 1, 2, 3, 4 ] ) ); // returns 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][mdn-iterator-protocol] protocol-compliant object has the following properties: - **next**: function which returns an [iterator][mdn-iterator-protocol] 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][mdn-iterator-protocol] is finished. - **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object. To invoke a callback upon skipping the last value of a provided [`iterator`][mdn-iterator-protocol], provide a `clbk` argument. ```javascript var array2iterator = require( '@stdlib/array/to-iterator' ); function onPop( v ) { console.log( v ); // => 4 } var it = iterPop( array2iterator( [ 1, 2, 3, 4 ] ), onPop ); // returns 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`. ```javascript 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 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][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
## Examples ```javascript 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`][@stdlib/iter/push]: create an iterator which appends additional values to the end of a provided iterator. - [`@stdlib/iter/shift`][@stdlib/iter/shift]: create an iterator which skips the first value of a provided iterator. - [`@stdlib/iter/slice`][@stdlib/iter/slice]: create an iterator which returns a subsequence of iterated values from a provided iterator.
[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol [@stdlib/iter/push]: https://github.com/stdlib-js/iter/tree/main/push [@stdlib/iter/shift]: https://github.com/stdlib-js/iter/tree/main/shift [@stdlib/iter/slice]: https://github.com/stdlib-js/iter/tree/main/slice