93 lines
3.7 KiB
Markdown
93 lines
3.7 KiB
Markdown
|
# es-get-iterator <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
|
||
|
|
|
||
|
|
[![Build Status][travis-svg]][travis-url]
|
||
|
|
[![dependency status][deps-svg]][deps-url]
|
||
|
|
[![dev dependency status][dev-deps-svg]][dev-deps-url]
|
||
|
|
[![License][license-image]][license-url]
|
||
|
|
[![Downloads][downloads-image]][downloads-url]
|
||
|
|
|
||
|
|
[![npm badge][npm-badge-png]][package-url]
|
||
|
|
|
||
|
|
Get an iterator for any JS language value. Works robustly across all environments, all versions.
|
||
|
|
|
||
|
|
In modern engines, `value[Symbol.iterator]()` is sufficient to produce an iterator (an object with a `.next` method) for that object. However, older engines:
|
||
|
|
- may lack `Symbol` support altogether
|
||
|
|
- may have `Symbol.iterator` but not implement it on everything it should, like arguments objects
|
||
|
|
- may have `Map` and `Set`, but a non-standard name for the iterator-producing method (`.iterator` or `['@@iterator']`, eg)
|
||
|
|
- may be old versions of Firefox that produce values until they throw a StopIteration exception, rather than having iteration result objects
|
||
|
|
- may be polyfilled/shimmed/shammed, with `es6-shim` or `core-js` or similar
|
||
|
|
|
||
|
|
This library attempts to provide an abstraction over all that complexity!
|
||
|
|
|
||
|
|
In node v13+, `exports` is used to provide a lean implementation that lacks all the complexity described above, in combination with the `browser` field so that bundlers will pick up the proper implementation.
|
||
|
|
|
||
|
|
## Targeting browsers with Symbol support
|
||
|
|
|
||
|
|
If you are targeting browsers that definitely all have Symbol support, then you can configure your bundler to replace `require('has-symbols')()` with a literal `true`, which should allow dead code elimination to reduce the size of the bundled code.
|
||
|
|
|
||
|
|
### With `@rollup/plugin-replace`
|
||
|
|
|
||
|
|
```js
|
||
|
|
// rollup.config.js
|
||
|
|
|
||
|
|
import replace from '@rollup/plugin-replace';
|
||
|
|
|
||
|
|
export default {
|
||
|
|
...
|
||
|
|
plugins: [
|
||
|
|
replace({
|
||
|
|
"require('has-symbols')()": 'true',
|
||
|
|
delimiters: ['', '']
|
||
|
|
})
|
||
|
|
]
|
||
|
|
};
|
||
|
|
```
|
||
|
|
|
||
|
|
## Example
|
||
|
|
|
||
|
|
```js
|
||
|
|
var getIterator = require('es-get-iterator');
|
||
|
|
var assert = require('assert');
|
||
|
|
|
||
|
|
var iterator = getIterator('a 💩');
|
||
|
|
assert.deepEqual(
|
||
|
|
[iterator.next(), iterator.next(), iterator.next(), iterator.next()],
|
||
|
|
[{ done: false, value: 'a' }, { done: false, value: ' ' }, { done: false, value: '💩' }, { done: true, value: undefined }]
|
||
|
|
);
|
||
|
|
|
||
|
|
var iterator = getIterator([1, 2]);
|
||
|
|
assert.deepEqual(
|
||
|
|
[iterator.next(), iterator.next(), iterator.next()],
|
||
|
|
[{ done: false, value: 1 }, { done: false, value: 2 }, { done: true, value: undefined }]
|
||
|
|
);
|
||
|
|
|
||
|
|
var iterator = getIterator(new Set([1, 2]));
|
||
|
|
assert.deepEqual(
|
||
|
|
[iterator.next(), iterator.next(), iterator.next()],
|
||
|
|
[{ done: false, value: 1 }, { done: false, value: 2 }, { done: true, value: undefined }]
|
||
|
|
);
|
||
|
|
|
||
|
|
var iterator = getIterator(new Map([[1, 2], [3, 4]]));
|
||
|
|
assert.deepEqual(
|
||
|
|
[iterator.next(), iterator.next(), iterator.next()],
|
||
|
|
[{ done: false, value: [1, 2] }, { done: false, value: [3, 4] }, { done: true, value: undefined }]
|
||
|
|
);
|
||
|
|
```
|
||
|
|
|
||
|
|
## Tests
|
||
|
|
Simply clone the repo, `npm install`, and run `npm test`
|
||
|
|
|
||
|
|
[package-url]: https://npmjs.org/package/es-get-iterator
|
||
|
|
[npm-version-svg]: http://versionbadg.es/ljharb/es-get-iterator.svg
|
||
|
|
[travis-svg]: https://travis-ci.org/ljharb/es-get-iterator.svg
|
||
|
|
[travis-url]: https://travis-ci.org/ljharb/es-get-iterator
|
||
|
|
[deps-svg]: https://david-dm.org/ljharb/es-get-iterator.svg
|
||
|
|
[deps-url]: https://david-dm.org/ljharb/es-get-iterator
|
||
|
|
[dev-deps-svg]: https://david-dm.org/ljharb/es-get-iterator/dev-status.svg
|
||
|
|
[dev-deps-url]: https://david-dm.org/ljharb/es-get-iterator#info=devDependencies
|
||
|
|
[npm-badge-png]: https://nodei.co/npm/es-get-iterator.png?downloads=true&stars=true
|
||
|
|
[license-image]: http://img.shields.io/npm/l/es-get-iterator.svg
|
||
|
|
[license-url]: LICENSE
|
||
|
|
[downloads-image]: http://img.shields.io/npm/dm/es-get-iterator.svg
|
||
|
|
[downloads-url]: http://npm-stat.com/charts.html?package=es-get-iterator
|