# iterStep > Create an iterator which returns a sequence of numbers according to a specified increment.
## Usage ```javascript var iterStep = require( '@stdlib/iter/step' ); ``` #### iterStep( start, increment\[, N] ) Returns an iterator which returns a sequence of numbers according to a specified `increment`. ```javascript var it = iterStep( 0, 2 ); // returns var v = it.next().value; // returns 0 v = it.next().value; // returns 2 v = it.next().value; // returns 4 // ... ``` 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. By default, the function returns an infinite iterator (i.e., an iterator which never ends). To limit the number of returned values, provide a third argument. ```javascript var it = iterStep( 0, 2, 3 ); // returns var v = it.next().value; // returns 0 v = it.next().value; // returns 2 v = it.next().value; // returns 4 var bool = it.next().done; // returns true ```
## Notes - The returned iterator is guaranteed to return the `start` value. Beware, however, that values subsequent to the `start` value are subject to floating-point rounding errors. For example, ```javascript var it = iterStep( 0.1, 0.2 ); // returns var v = it.next().value; // returns 0.1 v = it.next().value; // returns ~0.3 v = it.next().value; // returns 0.5 ``` If you desire more control over value precision, consider using [roundn][@stdlib/math/base/special/roundn]: ```javascript var roundn = require( '@stdlib/math/base/special/roundn' ); var iterMap = require( '@stdlib/iter/map' ); function round( v ) { return roundn( v, -2 ); } // Create an iterator returning values subject to floating-point errors: var it1 = iterStep( 0.1, 0.2, 10 ); // Create an iterator to round each value to the nearest hundredth: var it2 = iterMap( it1, roundn ); // Perform manual iteration... var v; while ( true ) { v = it2.next(); if ( v.done ) { break; } console.log( v.value ); } ``` - If an environment supports `Symbol.iterator`, the returned iterator is iterable.
## Examples ```javascript var iterStep = require( '@stdlib/iter/step' ); // Create an iterator which is subject to floating-point rounding errors: var it = iterStep( 0.0, 0.02, 50 ); // Perform manual iteration... var v; while ( true ) { v = it.next(); if ( v.done ) { break; } console.log( v.value ); } ```
* * * ## See Also - [`@stdlib/array/from-iterator`][@stdlib/array/from-iterator]: create (or fill) an array from an iterator. - [`@stdlib/iter/datespace`][@stdlib/iter/datespace]: create an iterator which returns evenly spaced dates over a specified interval. - [`@stdlib/iter/incrspace`][@stdlib/iter/incrspace]: create an iterator which returns evenly spaced numbers according to a specified increment. - [`@stdlib/iter/linspace`][@stdlib/iter/linspace]: create an iterator which returns evenly spaced numbers over a specified interval. - [`@stdlib/iter/logspace`][@stdlib/iter/logspace]: create an iterator which returns evenly spaced numbers on a log scale. - [`@stdlib/iter/unitspace`][@stdlib/iter/unitspace]: create an iterator which returns numbers incremented by one.
[@stdlib/math/base/special/roundn]: https://www.npmjs.com/package/@stdlib/math-base-special-roundn [@stdlib/array/from-iterator]: https://www.npmjs.com/package/@stdlib/array-from-iterator [@stdlib/iter/datespace]: https://github.com/stdlib-js/iter/tree/main/datespace [@stdlib/iter/incrspace]: https://github.com/stdlib-js/iter/tree/main/incrspace [@stdlib/iter/linspace]: https://github.com/stdlib-js/iter/tree/main/linspace [@stdlib/iter/logspace]: https://github.com/stdlib-js/iter/tree/main/logspace [@stdlib/iter/unitspace]: https://github.com/stdlib-js/iter/tree/main/unitspace