feat: implement FormData Iterator

lib/fetch/formdata.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const { isBlobLike, isFileLike, toUSVString } = require('./util')
+const { isBlobLike, isFileLike, toUSVString, makeIterator } = require('./util')
 const { kState } = require('./symbols')
 const { File, FileLike } = require('./file')
 const { Blob } = require('buffer')
@@ -187,45 +187,68 @@ class FormData {
     return this.constructor.name
   }
 
-  * entries () {
+  entries () {
     if (!(this instanceof FormData)) {
       throw new TypeError('Illegal invocation')
     }
 
-    for (const pair of this) {
-      yield pair
-    }
+    return makeIterator(
+      makeIterable(this[kState], 'entries'),
+      'FormData'
+    )
   }
 
-  * keys () {
+  keys () {
     if (!(this instanceof FormData)) {
       throw new TypeError('Illegal invocation')
     }
 
-    for (const [key] of this) {
-      yield key
+    return makeIterator(
+      makeIterable(this[kState], 'keys'),
+      'FormData'
+    )
+  }
+
+  values () {
+    if (!(this instanceof FormData)) {
+      throw new TypeError('Illegal invocation')
     }
+
+    return makeIterator(
+      makeIterable(this[kState], 'values'),
+      'FormData'
+    )
   }
 
-  * values () {
+  /**
+   * @param {(value: string, key: string, self: FormData) => void} callbackFn
+   * @param {unknown} thisArg
+   */
+  forEach (callbackFn, thisArg = globalThis) {
     if (!(this instanceof FormData)) {
       throw new TypeError('Illegal invocation')
     }
 
-    for (const [, value] of this) {
-      yield value
+    if (arguments.length < 1) {
+      throw new TypeError(
+        `Failed to execute 'forEach' on 'FormData': 1 argument required, but only ${arguments.length} present.`
+      )
     }
-  }
 
-  * [Symbol.iterator] () {
-    // The value pairs to iterate over are this’s entry list’s entries with
-    // the key being the name and the value being the value.
-    for (const { name, value } of this[kState]) {
-      yield [name, value]
+    if (typeof callbackFn !== 'function') {
+      throw new TypeError(
+        "Failed to execute 'forEach' on 'FormData': parameter 1 is not of type 'Function'."
+      )
+    }
+
+    for (const [key, value] of this) {
+      callbackFn.apply(thisArg, [value, key, this])
     }
   }
 }
 
+FormData.prototype[Symbol.iterator] = FormData.prototype.entries
+
 function makeEntry (name, value, filename) {
   // To create an entry for name, value, and optionally a filename, run these
   // steps:
@@ -267,4 +290,18 @@ function makeEntry (name, value, filename) {
   return entry
 }
 
+function * makeIterable (entries, type) {
+  // The value pairs to iterate over are this’s entry list’s entries
+  // with the key being the name and the value being the value.
+  for (const { name, value } of entries) {
+    if (type === 'entries') {
+      yield [name, value]
+    } else if (type === 'values') {
+      yield value
+    } else {
+      yield name
+    }
+  }
+}
+
 module.exports = { FormData }

lib/fetch/headers.js

@@ -6,6 +6,7 @@ const { validateHeaderName, validateHeaderValue } = require('http')
 const { kHeadersList } = require('../core/symbols')
 const { kGuard } = require('./symbols')
 const { kEnumerableProperty } = require('../core/util')
+const { makeIterator } = require('./util')
 
 const kHeadersMap = Symbol('headers map')
 const kHeadersSortedMap = Symbol('headers map sorted')
@@ -73,33 +74,6 @@ function fill (headers, object) {
   }
 }
 
-// https://tc39.es/ecma262/#sec-%25iteratorprototype%25-object
-const esIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
-
-// https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
-function makeHeadersIterator (iterator) {
-  const i = {
-    next () {
-      if (Object.getPrototypeOf(this) !== i) {
-        throw new TypeError(
-          '\'next\' called on an object that does not implement interface Headers Iterator.'
-        )
-      }
-
-      return iterator.next()
-    },
-    // The class string of an iterator prototype object for a given interface is the
-    // result of concatenating the identifier of the interface and the string " Iterator".
-    [Symbol.toStringTag]: 'Headers Iterator'
-  }
-
-  // The [[Prototype]] internal slot of an iterator prototype object must be %IteratorPrototype%.
-  Object.setPrototypeOf(i, esIteratorPrototype)
-  // esIteratorPrototype needs to be the prototype of i
-  // which is the prototype of an empty object. Yes, it's confusing.
-  return Object.setPrototypeOf({}, i)
-}
-
 class HeadersList {
   constructor (init) {
     if (init instanceof HeadersList) {
@@ -306,23 +280,23 @@ class Headers {
       throw new TypeError('Illegal invocation')
     }
 
-    return makeHeadersIterator(this[kHeadersSortedMap].keys())
+    return makeIterator(this[kHeadersSortedMap].keys(), 'Headers')
   }
 
   values () {
     if (!(this instanceof Headers)) {
       throw new TypeError('Illegal invocation')
     }
 
-    return makeHeadersIterator(this[kHeadersSortedMap].values())
+    return makeIterator(this[kHeadersSortedMap].values(), 'Headers')
   }
 
   entries () {
     if (!(this instanceof Headers)) {
       throw new TypeError('Illegal invocation')
     }
 
-    return makeHeadersIterator(this[kHeadersSortedMap].entries())
+    return makeIterator(this[kHeadersSortedMap].entries(), 'Headers')
   }
 
   /**

lib/fetch/util.js

@@ -361,6 +361,33 @@ function serializeJavascriptValueToJSONString (value) {
   return result
 }
 
+// https://tc39.es/ecma262/#sec-%25iteratorprototype%25-object
+const esIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
+
+// https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
+function makeIterator (iterator, name) {
+  const i = {
+    next () {
+      if (Object.getPrototypeOf(this) !== i) {
+        throw new TypeError(
+          `'next' called on an object that does not implement interface ${name} Iterator.`
+        )
+      }
+
+      return iterator.next()
+    },
+    // The class string of an iterator prototype object for a given interface is the
+    // result of concatenating the identifier of the interface and the string " Iterator".
+    [Symbol.toStringTag]: `${name} Iterator`
+  }
+
+  // The [[Prototype]] internal slot of an iterator prototype object must be %IteratorPrototype%.
+  Object.setPrototypeOf(i, esIteratorPrototype)
+  // esIteratorPrototype needs to be the prototype of i
+  // which is the prototype of an empty object. Yes, it's confusing.
+  return Object.setPrototypeOf({}, i)
+}
+
 module.exports = {
   isAborted,
   isCancelled,
@@ -390,5 +417,6 @@ module.exports = {
   isValidReasonPhrase,
   sameOrigin,
   normalizeMethod,
-  serializeJavascriptValueToJSONString
+  serializeJavascriptValueToJSONString,
+  makeIterator
 }

test/fetch/formdata.js

@@ -213,6 +213,65 @@ test('formData.values', (t) => {
   })
 })
 
+test('formData forEach', (t) => {
+  t.test('invalid arguments', (t) => {
+    t.throws(() => {
+      FormData.prototype.forEach.call({})
+    }, TypeError('Illegal invocation'))
+
+    t.throws(() => {
+      const fd = new FormData()
+
+      fd.forEach({})
+    }, TypeError)
+
+    t.end()
+  })
+
+  t.test('with a callback', (t) => {
+    const fd = new FormData()
+
+    fd.set('a', 'b')
+    fd.set('c', 'd')
+
+    let i = 0
+    fd.forEach((value, key, self) => {
+      if (i++ === 0) {
+        t.equal(value, 'b')
+        t.equal(key, 'a')
+      } else {
+        t.equal(value, 'd')
+        t.equal(key, 'c')
+      }
+
+      t.equal(fd, self)
+    })
+
+    t.end()
+  })
+
+  t.test('with a thisArg', (t) => {
+    const fd = new FormData()
+    fd.set('b', 'a')
+
+    fd.forEach(function (value, key, self) {
+      t.equal(this, globalThis)
+      t.equal(fd, self)
+      t.equal(key, 'b')
+      t.equal(value, 'a')
+    })
+
+    const thisArg = Symbol('thisArg')
+    fd.forEach(function () {
+      t.equal(this, thisArg)
+    }, thisArg)
+
+    t.end()
+  })
+
+  t.end()
+})
+
 test('formData toStringTag', (t) => {
   const form = new FormData()
   t.equal(form[Symbol.toStringTag], 'FormData')