An ESnext spec-compliant `Array.prototype.findLastIndex` shim/polyfill/replacement that works as far down as ES3.

Define multiple non-enumerable properties at once. Uses `Object.defineProperty` when available; falls back to standard assignment in older engines.

ES6 spec-compliant Object.assign shim. From https://github.com/es-shims/es6-shim

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

An ESnext spec-compliant `Array.prototype.findLast` shim/polyfill/replacement that works as far down as ES3.

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

An ES2019 spec-compliant `Array.prototype.flat` shim/polyfill/replacement that works as far down as ES3.

Determine if a function is a native generator function.

Is this specifier a node.js core module?

ES6 spec-compliant RegExp.prototype.flags shim.

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

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

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

Which kind of Collection (Map, Set, WeakMap, WeakSet) is this JavaScript value? Works cross-realm, without `instanceof`, and despite Symbol.toStringTag.

ES spec-like internal slots

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

ES proposal-spec-compliant Object.fromEntries shim.

Robustly `.call.bind()` a function

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

Helper package to shim a method into `Array.prototype[Symbol.unscopables]`