inspect-js

array-buffer-byte-length

Get the byte length of an ArrayBuffer, even in engines without a `.byteLength` method.

available-regexp-flags

Which regular expression flags does the current environment support?

available-typed-arrays

Returns an array of Typed Array names that are available in the current environment

data-view-buffer

Get the ArrayBuffer out of a DataView, robustly.

data-view-byte-length

Get the byteLength out of a DataView, robustly.

data-view-byte-offset

Get the byteOffset out of a DataView, robustly.

deep-equal

node's assert.deepEqual algorithm

deep-equal-json

`deep-equal`, but only for JSON-supported values.

defined

return the first argument that is `!== undefined`

functions-have-names

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

getprototypeof

An ES5 mostly-spec-compliant `Object.getPrototypeOf` sham/polyfill/replacement that works in as many engines as possible

get-symbol-description

Gets the description of a Symbol. Handles `Symbol()` vs `Symbol('')` properly when possible.

has-bigints

Determine if the JS environment has BigInt support.

has-dynamic-import

Does the current environment have `import()` support?

has-named-captures

Does the JS environment support named capture groups in regexes?

has-object-spread

check if the environment supports { ...a } spread syntax

has-optional-chaining

Determine if the JS environment has optional chaining support

has-override-mistake

Determine whether the environment has the so-called "override mistake" - [[Set]]ing a property whose ancestor is nonwritable throws.

hasown

A robust, ES3 compatible, "has own property" predicate.

has-package-exports

Does the current node version have support for the "exports" field in package.json?

has-package-imports

Does the current node version have support for the "imports" field in package.json?

has-package-self-reference

Does the current node version have support for requiring/importing its own name?

has-private-fields

Determine if the JS environment has private fields (`class { #x; }`) support.

has-property-descriptors

Does the environment have full property descriptor support? Handles IE 8's broken defineProperty/gOPD.

has-proto

Does this environment have the ability to get the [[Prototype]] of an object on creation with `__proto__`?