The definitive JavaScript type testing library
JavaScript
194
216 commits
updated Oct 24, 2025
The definitive JavaScript type testing library
To be or not to be? This is the library!
As a node.js module
$ npm install is
As a component
$ component install enricomarino/is
is.a (value, type) or is.type (value, type)is.defined (value)is.empty (value)is.equal (value, other)is.hosted (value, host)is.instance (value, constructor)is.instanceof (value, constructor) - deprecated, because in ES3 browsers, "instanceof" is a reserved wordis.nil (value)is.null (value) - deprecated, because in ES3 browsers, "null" is a reserved wordis.undef (value)is.undefined (value) - deprecated, because in ES3 browsers, "undefined" is a reserved wordis.args (value)is.arguments (value) - deprecated, because "arguments" is a reserved wordis.args.empty (value)is.array (value)is.array.empty (value)is.arraylike (value)is.bool (value)is.boolean (value) - deprecated, because in ES3 browsers, "boolean" is a reserved wordis.false (value) - deprecated, because in ES3 browsers, "false" is a reserved wordis.true (value) - deprecated, because in ES3 browsers, "true" is a reserved wordis.date (value)is.element (value)is.error (value)is.fn (value)is.function (value) - deprecated, because in ES3 browsers, "function" is a reserved wordis.number (value)is.infinite (value)is.decimal (value)is.divisibleBy (value, n)is.integer (value)is.int (value) - deprecated, because in ES3 browsers, "int" is a reserved wordis.maximum (value, others)is.minimum (value, others)is.nan (value)is.even (value)is.odd (value)is.ge (value, other)is.gt (value, other)is.le (value, other)is.lt (value, other)is.within (value, start, finish)is.object (value)is.regexp (value)is.string (value)is.base64 (value)is.hex (value)is.symbol (value)is.bigint (value)Overall
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npm
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Releases this year
The definitive JavaScript type testing library
JavaScript
194
216 commits
updated Oct 24, 2025
The definitive JavaScript type testing library
To be or not to be? This is the library!
As a node.js module
$ npm install is
As a component
$ component install enricomarino/is
is.a (value, type) or is.type (value, type)is.defined (value)is.empty (value)is.equal (value, other)is.hosted (value, host)is.instance (value, constructor)is.instanceof (value, constructor) - deprecated, because in ES3 browsers, "instanceof" is a reserved wordis.nil (value)is.null (value) - deprecated, because in ES3 browsers, "null" is a reserved wordis.undef (value)is.undefined (value) - deprecated, because in ES3 browsers, "undefined" is a reserved wordis.args (value)is.arguments (value) - deprecated, because "arguments" is a reserved wordis.args.empty (value)is.array (value)is.array.empty (value)is.arraylike (value)is.bool (value)is.boolean (value) - deprecated, because in ES3 browsers, "boolean" is a reserved wordis.false (value) - deprecated, because in ES3 browsers, "false" is a reserved wordis.true (value) - deprecated, because in ES3 browsers, "true" is a reserved wordis.date (value)is.element (value)is.error (value)is.fn (value)is.function (value) - deprecated, because in ES3 browsers, "function" is a reserved wordis.number (value)is.infinite (value)is.decimal (value)is.divisibleBy (value, n)is.integer (value)is.int (value) - deprecated, because in ES3 browsers, "int" is a reserved wordis.maximum (value, others)is.minimum (value, others)is.nan (value)is.even (value)is.odd (value)is.ge (value, other)is.gt (value, other)is.le (value, other)is.lt (value, other)is.within (value, start, finish)is.object (value)is.regexp (value)is.string (value)is.base64 (value)is.hex (value)is.symbol (value)is.bigint (value)Overall
Maintained
Code review
npm
Latest release
Releases this year