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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​

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​

"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.

[..."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.

"abc".match(/./); // [ "a" ]
"abc".replace(/./, "f"); // "fbc"

[..././[Symbol.matchAll]("abc")]; // [[ "a" ]]

See also​

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