3f:null 40:["$","title",null,{"children":"fundamental type handling | Riley | Observable"}] 46:T894,

fundamental type handling

This is a substitute for typeof and implicit boolean coercion. Normally, the ECMA standard states that typeof document.all === "undefined", which is counterintuitive. The main goal of these functions is to make this more intuitive. These functions operate on these concepts (against the standard):

typeof document.all === "object"
typeof null === "null"
!!document.all === true

The functions are designed to work without need for prototype checking and to work across realms.

`${typeOf.name}(value): string`

When provided one argument, the value, this will return "null" for null and "undefined" for undefined (following ===). In all other cases, ${typeOf.name}(v) === typeof v.

47:T66e,

`${isClass.name}(class, value): boolean | null`

This attempts to determine whether the provided value is an instance of the class provided. The argument class may be a class object or a string. (If a class object is passed, its name is used.) This works exclusively for global classes; the benefit is that, if the provided value is from a different JavaScript realm, then the global class is looked up in that realm. This has a behavior similar to ${Array.name}.${Array.isArray.name} but for every global class.

If the global class can be found, then a boolean is returned depending on whether the value was confirmed to be of that class. If the global class cannot be found, or the value is not an object, then null is returned. If the class provided is exactly null (not a string), then the function returns whether the value has no prototype.

`${isClass.name}(class, value): boolean | null`

48:Tc3b,isClass = { const getProto = globalThis.Reflect?.getPrototypeOf ? globalThis.Reflect.getPrototypeOf.bind(globalThis.Reflect) : Object.getPrototypeOf.bind(Object); const setDesc = globalThis.Reflect?.defineProperty ? globalThis.Reflect.defineProperty.bind(globalThis.Reflect) : Object.defineProperty.bind(Object); const getOwnStringKeys = globalThis.Reflect?.ownKeys ? globalThis.Reflect.ownKeys.bind(globalThis.Reflect) : Object.getOwnPropertyNames.bind(Object); setDesc(isClass, "proto", { enumerable: true, value: isClassOrProto }); for (let name of "BigInt Boolean Function Number Object String Symbol".split(/\s+/)) { if (typeof globalThis[name] === "function" && typeOf(globalThis[name]) === "function") { let f = function(value) { return this(name, value); } setDesc(f, "name", { enumerable: true, configurable: true, get: () => `is${name}` }); isClass[name] || setDesc(isClass, name, { enumerable: true, value: f }); isClassOrProto[name] || setDesc(isClassOrProto, name, { enumerable: true, value: f }); } } return isClass; // const protoNames = new Set("bigint boolean null number string symbol undefined".split(/\s+/)); // const realms = new WeakMap(); function isClassOrProto(className, value) { let t = typeOf(value); switch (t) { case "function": case "object": return isClass(className, value); } return classToString(className).toLowerCase() === typeOf(value); } function isClass(className, value) { switch (typeOf(value)) { case "function": case "object": break; default: return false; } if (className === null) { return getProto(value) === null; } if (getProto(value) === null) { return false; } className = classToString(className); let global; if (value instanceof {}.constructor) { // this realm global = globalThis; } else { // other realm let v, p; v = value; while (true) { p = getProto(v); if (p === null) { break; } v = p; } let Object = v.constructor; global = new (Object.getPrototypeOf(Object).constructor)(`return globalThis ?? this;`)(); if (global.globalThis !== global) { return null; } } let targetProto, p; if (className in global && isObj(global[className]) && value instanceof global[className]) { targetProto = global[className].prototype; if ((p = getProto(value)) === targetProto) { return true; } while (p !== null) { p = getProto(p); if (p === targetProto) { return true; } } } return false; } function classToString(className) { return typeof className === "string" ? className : (className = String(typeof className === "function" ? (className.name || className) : className)); } function isObj(value) { switch (typeOf(value)) { case "object": case "function": return true; } return false; } }49:[] 44:{"id":"74fe408ebe11ef9b","slug":"typeof","title":"fundamental type handling","thumbnail":"66a1f5832390f61333583d2cc51e7508053e8a2a2aa6edf5f6104a412c29880a","access_level":"public","create_time":"$D2023-07-16T21:44:12.445Z","update_time":"$D2023-07-24T16:07:58.410Z","view_time":null,"first_public_time":"$D2023-07-16T21:44:12.445Z","has_unpublished_edits":null,"fork":false,"stars":0,"starred":false,"owner":{"type":"team","id":"d2b7afa3a61febdf","login":"rmw4269","name":"Riley","avatar_url":"https://avatars-next.observableusercontent.com/839ad38e4ca0e32eaad7be29b5bc0c3a7f4304d5f91dd0f3642acf08015b6530","tier":"starter_2024","bio":"I enjoy spreadsheets and JavaScript way too much.","following":false},"version":145,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"817e538440b46e8a","login":"rmw4269","name":"Riley","avatar_url":"https://avatars-next.observableusercontent.com/839ad38e4ca0e32eaad7be29b5bc0c3a7f4304d5f91dd0f3642acf08015b6530","tier":null,"bio":"I enjoy spreadsheets and JavaScript way too much.\n\ntrust://Riley.science!","following":false}],"members":[{"type":"individual","id":"817e538440b46e8a","login":"rmw4269","name":"Riley","avatar_url":"https://avatars-next.observableusercontent.com/839ad38e4ca0e32eaad7be29b5bc0c3a7f4304d5f91dd0f3642acf08015b6530","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":{"id":"f315bea3064cd044","slug":"imports","title":"importables","owner":{"id":"d2b7afa3a61febdf","login":"rmw4269","name":"Riley"}},"type":"notebook","body":{"titling":"auto","title":"fundamental type handling","cells":[{"id":0,"value":"$46","pinned":false,"hidden":false,"mode":"html","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":17,"value":"Object.fromEntries([0, ()=>{}, 1n, \":3\", {}, document.all].map(v => [typeOf(v), v]))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":19,"value":"typeOf(document.all)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":6,"value":"function typeOf(value) {\n if (value === null) { return \"null\"; }\n if (value === undefined) { return \"undefined\"; }\n let t = typeof value;\n if (t === \"undefined\") { return \"object\"; }\n return t;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":52,"value":"

`${truthy.name}(value): boolean`

This returns true for truthy values and false in all other cases.

`${falsy.name}(value): boolean`

${falsy.name}(value) === !${truthy.name}(value)

`${ternary.name}(value): boolean | null`

This returns null for nullish values and ${truthy.name}(value) in all other cases.

`${nullish.name}(value): boolean`

This returns true for nullish values and false in all other cases.

`${isPrimitive.name}(value): boolean`

This returns whether or not the provided value is a primitive, which is anything but an object or a function.

","pinned":false,"hidden":false,"mode":"html","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":132,"value":"function isPrimitive(value) {\n if (arguments.length != 1) { throw new SyntaxError(`Exactly one argument is expected for ${isPrimitive.name}`); }\n switch (typeOf(value)) {\n case \"object\":\n case \"function\":\n return false;\n }\n return true;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":90,"value":"isClass(String, new String(NaN))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":126,"value":"isClass.proto.String(\"hello\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":92,"value":"new Promise((accept, reject) => {\n let gen = Generators.worker(String.raw`globalThis.addEventListener(\"message\", ({data}) => postMessage(eval(String(data))))`);\n gen.return && invalidation.then(() => gen.return());\n let worker = gen[Symbol.iterator]().next().value;\n worker.addEventListener(\"message\", ({data}) => accept(data), {passive: true, once: true});\n worker.postMessage(`[]`);\n invalidation.then(reject);\n})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":121,"value":"$47","pinned":false,"hidden":false,"mode":"html","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":76,"value":"$48","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W49","stdlib":"1"}} 45:"$44:body"