inspect-js

This github and npm organization houses JavaScript projects that help you look at stuff.

Predicates

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 instanceof or 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 instanceof or 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?

Comparisons

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

Environment

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 name property 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 [[Prototype]] 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.toStringTag support. 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 exports field support: version ranges, categories, etc.
• supports-preserve-symlinks-flag - - - Determine if the current node version supports the --preserve-symlinks flag.

Describe

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 .byteLength method.
• 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() vs Symbol('') 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.