TypeError: matchAll/replaceAll must be called with a global RegExp

The JavaScript exception "TypeError: matchAll/replaceAll must be called with a global RegExp" occurs when the {{jsxref("String.prototype.matchAll()")}} or {{jsxref("String.prototype.replaceAll()")}} method is used with a {{jsxref("RegExp")}} object that does not have the {{jsxref("RegExp/global", "global")}} flag set.

Message#

TypeError: String.prototype.matchAll called with a non-global RegExp argument (V8-based)
TypeError: String.prototype.replaceAll called with a non-global RegExp argument (V8-based)
TypeError: matchAll must be called with a global RegExp (Firefox)
TypeError: replaceAll must be called with a global RegExp (Firefox)
TypeError: String.prototype.matchAll argument must not be a non-global regular expression (Safari)
TypeError: String.prototype.replaceAll argument must not be a non-global regular expression (Safari)

Error type#

{{jsxref("TypeError")}}

What went wrong?#

The {{jsxref("String.prototype.matchAll()")}} and {{jsxref("String.prototype.replaceAll()")}} methods require a {{jsxref("RegExp")}} object with the {{jsxref("RegExp/global", "global")}} flag set. This flag indicates that the regular expression can match all locations of the input string, instead of stopping at the first match. Although the g flag is redundant when using these methods (because these methods always do a global replacement), they are still required to make the intention clear.

It's worth noting that the g flag validation is done in the matchAll and replaceAll methods. If you use the [Symbol.matchAll]() method of RegExp instead, you won't get this error, but there will only be a single match.

Examples#

Invalid cases#

```js example-bad "abc".matchAll(/./); // TypeError "abc".replaceAll(/./, "f"); // TypeError

### Valid cases

If you intend to do global matching/replacement: either add the `g` flag, or construct a new `RegExp` object with the `g` flag, if you want to keep the original regex unchanged.

```js example-good
[..."abc".matchAll(/./g)]; // [[ "a" ], [ "b" ], [ "c" ]]
"abc".replaceAll(/./g, "f"); // "fff"

const existingPattern = /./;
const newPattern = new RegExp(
  existingPattern.source,
  `${existingPattern.flags}g`,
);
"abc".replaceAll(newPattern, "f"); // "fff"

If you only intend to do a single matching/replacement: use {{jsxref("String.prototype.match()")}} or {{jsxref("String.prototype.replace()")}} instead. You can also use the [Symbol.matchAll]() method if you want an iterator like matchAll returns that only contains one match, but doing so will be very confusing.

```js example-good "abc".match(/./); // [ "a" ] "abc".replace(/./, "f"); // "fbc"

[..././Symbol.matchAll]; // [[ "a" ]] ```

See also#

• {{jsxref("String.prototype.matchAll()")}}
• {{jsxref("String.prototype.replaceAll()")}}
• {{jsxref("RegExp.prototype.global")}}