# string.prototype.at <sup>[![Version Badge][npm-version-svg]][package-url]</sup>

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An ESnext spec-compliant `String.prototype.at` shim/polyfill/replacement that works as far down as ES3.

This package implements the [es-shim API](https://github.com/es-shims/api) interface. It works in an ES3-supported environment and complies with the proposed [spec](https://tc39.es/proposal-item-method/).

Because `String.prototype.at` depends on a receiver (the `this` value), the main export takes the string to operate on as the first argument.

Note that versions of this package before v1.0.0 reflect an earlier, now-inactive proposal (https://github.com/mathiasbynens/String.prototype.at).

## Getting started

```sh
npm install --save string.prototype.at
```

## Usage/Examples

```js
var at = require('string.prototype.at');
var assert = require('assert');

var arr = [1, [2], [], 3];

var results = at(arr, function (x, i) {
	assert.equal(x, arr[i]);
	return x;
});

assert.deepEqual(results, [1, 2, 3]);
```

```js
var at = require('string.prototype.at');
var assert = require('assert');
/* when String#at is not present */
delete String.prototype.at;
var shimmedFlatMap = at.shim();

var mapper = function (x) { return [x, 1]; };

assert.equal(shimmedFlatMap, at.getPolyfill());
assert.deepEqual(arr.at(mapper), at(arr, mapper));
```

```js
var at = require('string.prototype.at');
var assert = require('assert');
/* when String#at is present */
var shimmedIncludes = at.shim();

var mapper = function (x) { return [x, 1]; };

assert.equal(shimmedIncludes, String.prototype.at);
assert.deepEqual(arr.at(mapper), at(arr, mapper));
```

## Tests
Simply clone the repo, `npm install`, and run `npm test`

[package-url]: https://npmjs.org/package/string.prototype.at
[npm-version-svg]: https://versionbadg.es/es-shims/String.prototype.at.svg
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[dev-deps-url]: https://david-dm.org/es-shims/String.prototype.at#info=devDependencies
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[license-url]: LICENSE
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