Inspect JS

is-callable

Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.

which-boxed-primitive

Which kind of boxed JS primitive is this?

is-string

Is this value a JS String object or primitive? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

is-symbol

Is this an ES6 Symbol value?

is-equal

Are these two values conceptually equal?

is-generator-function

Is this an ES6 generator function?

has-bigints

Determine if the JS environment has BigInt support.

is-boxed-primitive

Polyfill/shim for node's `util.isBoxedPrimitive()`

which-typed-array

Which kind of Typed Array is this JavaScript value? Works cross-realm, without `instanceof`, and despite Symbol.toStringTag.

is-typed-array

Is this value a JS Typed Array? This module works cross-realm/iframe, does not depend on `instanceof` or mutable properties, and despite ES6 Symbol.toStringTag.

is-boolean-object

Is this value a JS Boolean? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

is-arrow-function

Determine if a function is an ES6 arrow function or not.

is-date-object

Is this value a JS Date object? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

is-regex

Is this value a JS regex?

is-arguments

Is this an arguments object? It's a harder question than you think.

is-number-object

Is this value a JS Number object? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

has-symbols

Determine if the JS environment has Symbol support. Supports spec, or shams.

functions-have-names

Does this JS environment support the `name` property on functions?

has-strict-mode

Does the current JS environment have strict mode? ES5+ should; but let's not assume.

has-template-literals

Determine if the JS environment has template literal support

is-negative-zero

Is this value negative zero? === will lie to you.

is-bigint

is-object

Checks whether a value is an object, because typeof is a troll