String.prototype.matchAll()
===========================

The **`matchAll()`** method of `String` values returns an iterator of all results matching this string against a regular expression, including capturing groups.

Try it
------

Syntax
------


```js
matchAll(regexp)
```

### Parameters

`regexp`

A regular expression object, or any object that has a `Symbol.matchAll` method.

If `regexp` is not a `RegExp` object and does not have a `Symbol.matchAll` method, it is implicitly converted to a `RegExp` by using `new RegExp(regexp, 'g')`.

If `regexp` is a regex, then it must have the global (`g`) flag set, or a `TypeError` is thrown.

### Return value

An iterable iterator object (which is not restartable) of matches or an empty iterator if no matches are found. Each value yielded by the iterator is an array with the same shape as the return value of `RegExp.prototype.exec()`.

### Exceptions

`TypeError`

Thrown if the `regexp` is a regex that does not have the global (`g`) flag set (its `flags` property does not contain `"g"`).

Description
-----------

The implementation of `String.prototype.matchAll` itself is very simple — it simply calls the `Symbol.matchAll` method of the argument with the string as the first parameter (apart from the extra input validation that the regex is global). The actual implementation comes from `RegExp.prototype[@@matchAll]()`.

Examples
--------

### Regexp.prototype.exec() and matchAll()

Without `matchAll()`, it's possible to use calls to `regexp.exec()` (and regexes with the `g` flag) in a loop to obtain all the matches:


```js
const regexp = /foo[a-z]\*/g;
const str = "table football, foosball";
let match;

while ((match = regexp.exec(str)) !== null) {
  console.log(
    `Found ${match[0]} start=${match.index} end=${regexp.lastIndex}.`,
  );
}
// Found football start=6 end=14.
// Found foosball start=16 end=24.
```


With `matchAll()` available, you can avoid the `while` loop and `exec` with `g`. Instead, you get an iterator to use with the more convenient `for...of`, array spreading, or `Array.from()` constructs:


```js
const regexp = /foo[a-z]\*/g;
const str = "table football, foosball";
const matches = str.matchAll(regexp);

for (const match of matches) {
  console.log(
    `Found ${match[0]} start=${match.index} end=${
 match.index + match[0].length
 }.`,
  );
}
// Found football start=6 end=14.
// Found foosball start=16 end=24.

// matches iterator is exhausted after the for...of iteration
// Call matchAll again to create a new iterator
Array.from(str.matchAll(regexp), (m) => m[0]);
// [ "football", "foosball" ]
```


`matchAll` will throw an exception if the `g` flag is missing.


```js
const regexp = /[a-c]/;
const str = "abc";
str.matchAll(regexp);
// TypeError
```


`matchAll` internally makes a clone of the `regexp` — so, unlike `regexp.exec()`, `lastIndex` does not change as the string is scanned.


```js
const regexp = /[a-c]/g;
regexp.lastIndex = 1;
const str = "abc";
Array.from(str.matchAll(regexp), (m) => `${regexp.lastIndex} ${m[0]}`);
// [ "1 b", "1 c" ]
```


However, this means that unlike using `regexp.exec()` in a loop, you can't mutate `lastIndex` to make the regex advance or rewind.

### Better access to capturing groups (than String.prototype.match())

Another compelling reason for `matchAll` is the improved access to capture groups.

Capture groups are ignored when using `match()` with the global `g` flag:


```js
const regexp = /t(e)(st(\d?))/g;
const str = "test1test2";

str.match(regexp); // ['test1', 'test2']
```


Using `matchAll`, you can access capture groups easily:


```js
const array = [...str.matchAll(regexp)];

array[0];
// ['test1', 'e', 'st1', '1', index: 0, input: 'test1test2', length: 4]
array[1];
// ['test2', 'e', 'st2', '2', index: 5, input: 'test1test2', length: 4]
```

### Using matchAll() with a non-RegExp implementing @@matchAll

If an object has a `Symbol.matchAll` method, it can be used as a custom matcher. The return value of `Symbol.matchAll` becomes the return value of `matchAll()`.


```js
const str = "Hmm, this is interesting.";

str.matchAll({
  [Symbol.matchAll](str) {
    return [["Yes, it's interesting."]];
  },
}); // returns [["Yes, it's interesting."]]
```

Specifications
--------------

| Specification |
| --- |
| ECMAScript Language Specification # sec-string.prototype.matchall |

Browser compatibility
---------------------

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See also
--------

* Polyfill of `String.prototype.matchAll` in `core-js`
* `String.prototype.match()`
* Regular expressions guide
* Groups and backreferences guide
* `RegExp`
* `RegExp.prototype.exec()`
* `RegExp.prototype.test()`
* `RegExp.prototype[@@matchAll]()`