Checks if value is classified as a RegExp object. Part of Lodash Lang (stable — not deprecated). Note: a string like "/abc/" is not a RegExp — official docs show _.isRegExp('/abc/') → false.
Pass the value you want to inspect or convert. Read the return type carefully before you use the result.
Call _.isRegExp. Start with this line.
_.isRegExp(value)| Call | What it does |
|---|---|
_.isRegExp(value) | Primary signature. |
Prefer import isRegexp from "lodash/isRegexp" when you want a smaller bundle.
_.isRegExp(value)| Parameter | Description |
|---|---|
| value | Required. Value to check |
| Return Value | Description |
|---|---|
| * | true if RegExp, else false |
Only a real RegExp instance returns true.
console.log(_.isRegExp(/abc/)); // true
console.log(_.isRegExp('/abc/')); // false/abc/ creates a RegExp object → true.'/abc/' is text that only looks like a pattern → false.new RegExp(...) Also PassesConstructor-built regexes are real RegExp objects too.
var re = new RegExp("abc", "i");
console.log(_.isRegExp(re)); // true
console.log(re.test("ABC")); // truenew RegExp("abc", "i") builds a RegExp.isRegExp → true.test("ABC") succeeds.Pair isRegExp with isString when input may be either.
function asRegExp(value) {
if (_.isRegExp(value)) {
return value;
}
if (_.isString(value)) {
return new RegExp(value);
}
return null;
}
console.log(_.isRegExp(asRegExp(/hi/))); // true
console.log(_.isRegExp(asRegExp("hi"))); // true
console.log(asRegExp(42)); // nullnew RegExp.null.Shape is not enough — it must be a real RegExp.
var fake = { source: "abc", flags: "i", test: function () { return true; } };
console.log(_.isObjectLike(fake)); // true
console.log(_.isRegExp(fake)); // false
console.log(_.isRegExp(/abc/i)); // truesource / test but is a plain object.false./abc/i passes..test()Avoid runtime errors when the matcher is unknown.
function matches(matcher, text) {
if (!_.isRegExp(matcher)) {
return false;
}
return matcher.test(text);
}
console.log(matches(/ad/, "Ada")); // true
console.log(matches("/ad/", "Ada")); // false
console.log(matches(null, "Ada")); // false.test() unless the matcher is a RegExp."Ada"..test on a string would throw a TypeError._.isRegExp is a Lodash Lang helper available in 4.x (and earlier builds). It runs anywhere Lodash runs — modern browsers (via CDN or bundle) and Node.js / Bun / Deno with npm install lodash. Native engines offer instanceof RegExp; Lodash uses tag-based classification for more consistent cross-realm checks.
Available in [email protected] full builds and the lodash/isRegExp modular import. Works in evergreen browsers and current Node LTS when Lodash is installed.
Bottom line: Safe for production once Lodash is on the page or in your bundle. Prefer import isRegExp from "lodash/isRegExp" for smaller builds. Remember: '/abc/' is a string, not a RegExp.
Check whether a value is a safe integer number.
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