change webidl.util.Type return to an enum value

lib/web/fetch/headers.js

@@ -645,7 +645,7 @@ Object.defineProperties(Headers.prototype, {
 })
 
 webidl.converters.HeadersInit = function (V, prefix, argument) {
-  if (webidl.util.Type(V) === 'Object') {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT) {
     const iterator = Reflect.get(V, Symbol.iterator)
 
     // A work-around to ensure we send the properly-cased Headers when V is a Headers object.

lib/web/fetch/webidl.js

@@ -3,6 +3,15 @@
 const { types, inspect } = require('node:util')
 const { toUSVString } = require('../../core/util')
 
+const UNDEFINED = 1
+const BOOLEAN = 2
+const STRING = 3
+const SYMBOL = 4
+const NUMBER = 5
+const BIGINT = 6
+const NULL = 7
+const OBJECT = 8 // function and object
+
 /** @type {import('../../../types/webidl').Webidl} */
 const webidl = {}
 webidl.converters = {}
@@ -69,23 +78,47 @@ webidl.illegalConstructor = function () {
 // https://tc39.es/ecma262/#sec-ecmascript-data-types-and-values
 webidl.util.Type = function (V) {
   switch (typeof V) {
-    case 'undefined': return 'Undefined'
-    case 'boolean': return 'Boolean'
-    case 'string': return 'String'
-    case 'symbol': return 'Symbol'
-    case 'number': return 'Number'
-    case 'bigint': return 'BigInt'
+    case 'undefined': return UNDEFINED
+    case 'boolean': return BOOLEAN
+    case 'string': return STRING
+    case 'symbol': return SYMBOL
+    case 'number': return NUMBER
+    case 'bigint': return BIGINT
     case 'function':
     case 'object': {
       if (V === null) {
-        return 'Null'
+        return NULL
       }
 
-      return 'Object'
+      return OBJECT
     }
   }
 }
 
+webidl.util.Types = {
+  UNDEFINED,
+  BOOLEAN,
+  STRING,
+  SYMBOL,
+  NUMBER,
+  BIGINT,
+  NULL,
+  OBJECT
+}
+
+webidl.util.TypeValueToString = function (o) {
+  switch (webidl.util.Type(o)) {
+    case UNDEFINED: return 'Undefined'
+    case BOOLEAN: return 'Boolean'
+    case STRING: return 'String'
+    case SYMBOL: return 'Symbol'
+    case NUMBER: return 'Number'
+    case BIGINT: return 'BigInt'
+    case NULL: return 'Null'
+    case OBJECT: return 'Object'
+  }
+}
+
 // https://webidl.spec.whatwg.org/#abstract-opdef-converttoint
 webidl.util.ConvertToInt = function (V, bitLength, signedness, opts) {
   let upperBound
@@ -224,11 +257,11 @@ webidl.util.Stringify = function (V) {
   const type = webidl.util.Type(V)
 
   switch (type) {
-    case 'Symbol':
+    case SYMBOL:
       return `Symbol(${V.description})`
-    case 'Object':
+    case OBJECT:
       return inspect(V)
-    case 'String':
+    case STRING:
       return `"${V}"`
     default:
       return `${V}`
@@ -239,7 +272,7 @@ webidl.util.Stringify = function (V) {
 webidl.sequenceConverter = function (converter) {
   return (V, prefix, argument, Iterable) => {
     // 1. If Type(V) is not Object, throw a TypeError.
-    if (webidl.util.Type(V) !== 'Object') {
+    if (webidl.util.Type(V) !== OBJECT) {
       throw webidl.errors.exception({
         header: prefix,
         message: `${argument} (${webidl.util.Stringify(V)}) is not iterable.`
@@ -282,10 +315,10 @@ webidl.sequenceConverter = function (converter) {
 webidl.recordConverter = function (keyConverter, valueConverter) {
   return (O, prefix, argument) => {
     // 1. If Type(O) is not Object, throw a TypeError.
-    if (webidl.util.Type(O) !== 'Object') {
+    if (webidl.util.Type(O) !== OBJECT) {
       throw webidl.errors.exception({
         header: prefix,
-        message: `${argument} ("${webidl.util.Type(O)}") is not an Object.`
+        message: `${argument} ("${webidl.util.TypeValueToString(O)}") is not an Object.`
       })
     }
 
@@ -356,7 +389,7 @@ webidl.dictionaryConverter = function (converters) {
   return (dictionary, prefix, argument) => {
     const dict = {}
 
-    if (dictionary != null && webidl.util.Type(dictionary) !== 'Object') {
+    if (dictionary != null && webidl.util.Type(dictionary) !== OBJECT) {
       throw webidl.errors.exception({
         header: prefix,
         message: `Expected ${dictionary} to be one of: Null, Undefined, Object.`
@@ -532,7 +565,7 @@ webidl.converters.ArrayBuffer = function (V, prefix, argument, opts) {
   // see: https://tc39.es/ecma262/#sec-properties-of-the-arraybuffer-instances
   // see: https://tc39.es/ecma262/#sec-properties-of-the-sharedarraybuffer-instances
   if (
-    webidl.util.Type(V) !== 'Object' ||
+    webidl.util.Type(V) !== OBJECT ||
     !types.isAnyArrayBuffer(V)
   ) {
     throw webidl.errors.conversionFailed({
@@ -576,7 +609,7 @@ webidl.converters.TypedArray = function (V, T, prefix, name, opts) {
   //    [[TypedArrayName]] internal slot with a value
   //    equal to T’s name, then throw a TypeError.
   if (
-    webidl.util.Type(V) !== 'Object' ||
+    webidl.util.Type(V) !== OBJECT ||
     !types.isTypedArray(V) ||
     V.constructor.name !== T.name
   ) {
@@ -617,7 +650,7 @@ webidl.converters.TypedArray = function (V, T, prefix, name, opts) {
 webidl.converters.DataView = function (V, prefix, name, opts) {
   // 1. If Type(V) is not Object, or V does not have a
   //    [[DataView]] internal slot, then throw a TypeError.
-  if (webidl.util.Type(V) !== 'Object' || !types.isDataView(V)) {
+  if (webidl.util.Type(V) !== OBJECT || !types.isDataView(V)) {
     throw webidl.errors.exception({
       header: prefix,
       message: `${name} is not a DataView.`

lib/web/websocket/websocket.js

@@ -758,7 +758,7 @@ webidl.converters['sequence<DOMString>'] = webidl.sequenceConverter(
 )
 
 webidl.converters['DOMString or sequence<DOMString>'] = function (V, prefix, argument) {
-  if (webidl.util.Type(V) === 'Object' && Symbol.iterator in V) {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT && Symbol.iterator in V) {
     return webidl.converters['sequence<DOMString>'](V)
   }
 
@@ -784,15 +784,15 @@ webidl.converters.WebSocketInit = webidl.dictionaryConverter([
 ])
 
 webidl.converters['DOMString or sequence<DOMString> or WebSocketInit'] = function (V) {
-  if (webidl.util.Type(V) === 'Object' && !(Symbol.iterator in V)) {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT && !(Symbol.iterator in V)) {
     return webidl.converters.WebSocketInit(V)
   }
 
   return { protocols: webidl.converters['DOMString or sequence<DOMString>'](V) }
 }
 
 webidl.converters.WebSocketSendData = function (V) {
-  if (webidl.util.Type(V) === 'Object') {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT) {
     if (V instanceof Blob) {
       return V
     }

test/webidl/converters.js

@@ -238,3 +238,12 @@ test('webidl.util.Stringify', (t) => {
     assert.deepStrictEqual(webidl.util.Stringify(value), expected)
   }
 })
+
+test('recordConverter', () => {
+  const anyConverter = webidl.recordConverter(webidl.converters.any, webidl.converters.any)
+
+  assert.throws(
+    () => anyConverter(null, 'prefix', 'argument'),
+    new TypeError('prefix: argument ("Null") is not an Object.')
+  )
+})

test/webidl/util.js

@@ -6,15 +6,17 @@ const { webidl } = require('../../lib/web/fetch/webidl')
 
 test('Type(V)', () => {
   const Type = webidl.util.Type
-
-  assert.equal(Type(undefined), 'Undefined')
-  assert.equal(Type(null), 'Null')
-  assert.equal(Type(true), 'Boolean')
-  assert.equal(Type('string'), 'String')
-  assert.equal(Type(Symbol('symbol')), 'Symbol')
-  assert.equal(Type(1.23), 'Number')
-  assert.equal(Type(1n), 'BigInt')
-  assert.equal(Type({ a: 'b' }), 'Object')
+  const Types = webidl.util.Types
+
+  assert.equal(Type(undefined), Types.UNDEFINED)
+  assert.equal(Type(null), Types.NULL)
+  assert.equal(Type(true), Types.BOOLEAN)
+  assert.equal(Type('string'), Types.STRING)
+  assert.equal(Type(Symbol('symbol')), Types.SYMBOL)
+  assert.equal(Type(1.23), Types.NUMBER)
+  assert.equal(Type(1n), Types.BIGINT)
+  assert.equal(Type({ a: 'b' }), Types.OBJECT)
+  assert.equal(Type(function () {}), Types.OBJECT)
 })
 
 test('ConvertToInt(V)', () => {

types/webidl.d.ts

@@ -34,11 +34,24 @@ interface WebidlErrors {
   }): TypeError
 }
 
+interface WebIDLTypes {
+  UNDEFINED: 1,
+  BOOLEAN: 2,
+  STRING: 3,
+  SYMBOL: 4,
+  NUMBER: 5,
+  BIGINT: 6,
+  NULL: 7
+  OBJECT: 8
+}
+
 interface WebidlUtil {
   /**
    * @see https://tc39.es/ecma262/#sec-ecmascript-data-types-and-values
    */
-  Type (object: unknown):
+  Type (object: unknown): WebIDLTypes
+
+  TypeValueToString (o: unknown):
     | 'Undefined'
     | 'Boolean'
     | 'String'
@@ -48,6 +61,8 @@ interface WebidlUtil {
     | 'Null'
     | 'Object'
 
+  Types: WebIDLTypes
+
   /**
    * @see https://webidl.spec.whatwg.org/#abstract-opdef-converttoint
    */