This and npm organization houses JavaScript projects that help you look at stuff.
Functions that ask a question and produce a yes or no answer (`true` or `false`).
- defined -
- 
- return the first argument that is !== undefined - is-accessor-descriptor - - - Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.
- is-arguments - - - Is this an arguments object? It's a harder question than you think.
- is-array-buffer - - - Is this value a JS ArrayBuffer?
- is-arrow-function - - - Determine if a function is an ES6 arrow function or not.
- is-async-function - - - Determine if a function is a native async function.
- is-bigint - - - Is this value an ES BigInt?
- is-boolean-object - - - Is this value a JS Boolean? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-boxed-primitive - - - Is this value a boxed primitive? Shim for node's util.isBoxedPrimitive.
- is-callable - - - Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.
- is-core-module - - - Is this specifier a node.js core module?
- is-data-descriptor - - - Returns true if a value has the characteristics of a valid JavaScript data descriptor.
- is-data-view - - - Is this value a JS DataView? This module works cross-realm/iframe, does not depend on
instanceofor mutable properties, and despite ES6 Symbol.toStringTag. - is-date-object - - - Is this value a JS Date object? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-descriptor - - - Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.
- is-finalizationregistry - - - Is this value a JS FinalizationRegistry? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-generator-function - - - Determine if a function is a native generator function.
- is-map - - - Is this value a JS Map? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-negative-zero - - - Is this value negative zero? === will lie to you
- is-number-object - - - Is this value a JS Number object? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-object - - - Checks whether a value is an object
- is-package-root - - - Is this directory path the root of a package?
- is-regex - - - Is this value a JS regex? Works cross-realm/iframe, and despite ES6 @@toStringTag
- is-registered-symbol - - - Is this value a Symbol stored in the global cross-realm Symbol registry?
- is-set - - - Is this value a JS Set? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-shared-array-buffer - - - Is this value a JS SharedArrayBuffer?
- is-string - - - Is this value a JS String object or primitive? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-symbol - - - Determine if a value is an ES6 Symbol or not.
- is-typed-array - - - Is this value a JS Typed Array? This module works cross-realm/iframe, does not depend on
instanceofor mutable properties, and despite ES6 Symbol.toStringTag. - is-weakmap - - - Is this value a JS WeakMap? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-weakref - - - Is this value a JS WeakRef? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-weakset - - - Is this value a JS WeakSet? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
- is-well-known-symbol - - - Is this value a well-known Symbol?
Packages that compare two things.
- buffer-equal - - - return whether two buffers are equal
- deep-equal-json - - -
deep-equal, but only for JSON-supported values. - is-equal - - - Are these two values conceptually equal?
- deep-equal - - - node's assert.deepEqual algorithm
Packages that tell you about the JS env.
- 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
- functions-have-names - - - Does this JS environment support the
nameproperty on functions? - 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.
- 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 [[]] of an object on creation with
__proto__? - has-strict-mode - - - Does the current JS environment have strict mode? ES5+ should; but let's not assume.
- has-symbols - - - Determine if the JS environment has Symbol support. Supports spec, or shams.
- has-template-literals - - - Determine if the JS environment has template literal support.
- has-tostringtag - - - Determine if the JS environment has
Symbol.toStringTagsupport. Supports spec, or shams. - has-typed-arrays - - - Does this environment have JS Typed Arrays?
- hasown - - - A robust, ES3 compatible, "has own property" predicate.
- node-exports-info - - - Info about node
exportsfield support: version ranges, categories, etc. - supports-preserve-symlinks-flag - - - Determine if the current node version supports the
--preserve-symlinksflag.
Packages that tell you about a specific JS value.
- array-buffer-byte-length - - - Get the byte length of an ArrayBuffer, even in engines without a
.byteLengthmethod. - 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.
- get-symbol-description - - - Gets the description of a Symbol. Handles
Symbol()vsSymbol('')properly when possible. - object-inspect - - - string representations of objects in node and the browser
- typed-array-buffer - - - Get the ArrayBuffer out of a TypedArray, robustly.
- typed-array-byte-length - - - Robustly get the byte length of a Typed Array
- typed-array-byte-offset - - - Robustly get the byte offset of a Typed Array
- typed-array-length - - - Robustly get the length of a Typed Array
- which-boxed-primitive - - - Which kind of boxed JS primitive is this?
- which-builtin-type - - - What is the type of this builtin JS value?
- which-collection - - - Which kind of Collection (Map, Set, WeakMap, WeakSet) is this JavaScript value? Works cross-realm, without
instanceof, and despite Symbol.toStringTag. - which-typed-array - - - Which kind of Typed Array is this JavaScript value? Works cross-realm, without
instanceof, and despite Symbol.toStringTag.