url: improve URLSearchParams spec compliance

- Make URLSearchParams constructor spec-compliant
- Strip leading `?` in URL#search's setter
- Spec-compliant iterable interface
- More precise handling of update steps as mandated by the spec
- Add class strings to URLSearchParams objects and their prototype
- Make sure `this instanceof URLSearchParams` in methods

Also included are relevant tests from W3C's Web Platform Tests
(https://github.com/w3c/web-platform-tests/tree/master/url).

Fixes: https://github.com/nodejs/node/issues/9302
PR-URL: https://github.com/nodejs/node/pull/9484
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/url.js

@@ -20,6 +20,11 @@ const kHost = Symbol('host');
 const kPort = Symbol('port');
 const kDomain = Symbol('domain');
 
+// https://tc39.github.io/ecma262/#sec-%iteratorprototype%-object
+const IteratorPrototype = Object.getPrototypeOf(
+  Object.getPrototypeOf([][Symbol.iterator]())
+);
+
 function StorageObject() {}
 StorageObject.prototype = Object.create(null);
 
@@ -92,7 +97,8 @@ class URL {
         this[context].query = query;
         this[context].fragment = fragment;
         this[context].host = host;
-        this[searchParams] = new URLSearchParams(this);
+        this[searchParams] = new URLSearchParams(query);
+        this[searchParams][context] = this;
       });
   }
 
@@ -309,8 +315,31 @@ class URL {
   }
 
   set search(search) {
-    update(this, search);
-    this[searchParams][searchParams] = querystring.parse(this.search);
+    search = String(search);
+    if (search[0] === '?') search = search.slice(1);
+    if (!search) {
+      this[context].query = null;
+      this[context].flags &= ~binding.URL_FLAGS_HAS_QUERY;
+      this[searchParams][searchParams] = {};
+      return;
+    }
+    this[context].query = '';
+    binding.parse(search,
+                  binding.kQuery,
+                  null,
+                  this[context],
+      (flags, protocol, username, password,
+       host, port, path, query, fragment) => {
+        if (flags & binding.URL_FLAGS_FAILED)
+          return;
+        if (query) {
+          this[context].query = query;
+          this[context].flags |= binding.URL_FLAGS_HAS_QUERY;
+        } else {
+          this[context].flags &= ~binding.URL_FLAGS_HAS_QUERY;
+        }
+      });
+    this[searchParams][searchParams] = querystring.parse(search);
   }
 
   get hash() {
@@ -484,76 +513,129 @@ function encodeAuth(str) {
   return out;
 }
 
-function update(url, search) {
-  search = String(search);
-  if (!search) {
-    url[context].query = null;
-    url[context].flags &= ~binding.URL_FLAGS_HAS_QUERY;
+function update(url, params) {
+  if (!url)
     return;
+
+  url[context].query = params.toString();
+}
+
+function getSearchParamPairs(target) {
+  const obj = target[searchParams];
+  const keys = Object.keys(obj);
+  const values = [];
+  for (var i = 0; i < keys.length; i++) {
+    const name = keys[i];
+    const value = obj[name];
+    if (Array.isArray(value)) {
+      for (const item of value)
+        values.push([name, item]);
+    } else {
+      values.push([name, value]);
+    }
   }
-  if (search[0] === '?') search = search.slice(1);
-  url[context].query = '';
-  binding.parse(search,
-                binding.kQuery,
-                null,
-                url[context],
-    (flags, protocol, username, password,
-     host, port, path, query, fragment) => {
-      if (flags & binding.URL_FLAGS_FAILED)
-        return;
-      if (query) {
-        url[context].query = query;
-        url[context].flags |= binding.URL_FLAGS_HAS_QUERY;
-      } else {
-        url[context].flags &= ~binding.URL_FLAGS_HAS_QUERY;
-      }
-    });
+  return values;
 }
 
 class URLSearchParams {
-  constructor(url) {
-    this[context] = url;
-    this[searchParams] = querystring.parse(url[context].search || '');
+  constructor(init = '') {
+    if (init instanceof URLSearchParams) {
+      const childParams = init[searchParams];
+      this[searchParams] = Object.assign(Object.create(null), childParams);
+    } else {
+      init = String(init);
+      if (init[0] === '?') init = init.slice(1);
+      this[searchParams] = querystring.parse(init);
+    }
+
+    // "associated url object"
+    this[context] = null;
+
+    // Class string for an instance of URLSearchParams. This is different from
+    // the class string of the prototype object (set below).
+    Object.defineProperty(this, Symbol.toStringTag, {
+      value: 'URLSearchParams',
+      writable: false,
+      enumerable: false,
+      configurable: true
+    });
   }
 
   append(name, value) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 2) {
+      throw new TypeError(
+        'Both `name` and `value` arguments need to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     value = String(value);
     var existing = obj[name];
-    if (!existing) {
+    if (existing === undefined) {
       obj[name] = value;
     } else if (Array.isArray(existing)) {
       existing.push(value);
     } else {
       obj[name] = [existing, value];
     }
-    update(this[context], querystring.stringify(obj));
+    update(this[context], this);
   }
 
   delete(name) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 1) {
+      throw new TypeError('The `name` argument needs to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     delete obj[name];
-    update(this[context], querystring.stringify(obj));
+    update(this[context], this);
   }
 
   set(name, value) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 2) {
+      throw new TypeError(
+        'Both `name` and `value` arguments need to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     value = String(value);
     obj[name] = value;
-    update(this[context], querystring.stringify(obj));
+    update(this[context], this);
   }
 
   get(name) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 1) {
+      throw new TypeError('The `name` argument needs to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     var value = obj[name];
-    return Array.isArray(value) ? value[0] : value;
+    return value === undefined ? null : Array.isArray(value) ? value[0] : value;
   }
 
   getAll(name) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 1) {
+      throw new TypeError('The `name` argument needs to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     var value = obj[name];
@@ -561,28 +643,143 @@ class URLSearchParams {
   }
 
   has(name) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 1) {
+      throw new TypeError('The `name` argument needs to be specified');
+    }
+
     const obj = this[searchParams];
     name = String(name);
     return name in obj;
   }
 
-  *[Symbol.iterator]() {
-    const obj = this[searchParams];
-    for (const name in obj) {
-      const value = obj[name];
-      if (Array.isArray(value)) {
-        for (const item of value)
-          yield [name, item];
-      } else {
-        yield [name, value];
-      }
+  // https://heycam.github.io/webidl/#es-iterators
+  // Define entries here rather than [Symbol.iterator] as the function name
+  // must be set to `entries`.
+  entries() {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
     }
+
+    return createSearchParamsIterator(this, 'key+value');
   }
 
+  forEach(callback, thisArg = undefined) {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+    if (arguments.length < 1) {
+      throw new TypeError('The `callback` argument needs to be specified');
+    }
+
+    let pairs = getSearchParamPairs(this);
+
+    var i = 0;
+    while (i < pairs.length) {
+      const [key, value] = pairs[i];
+      callback.call(thisArg, value, key, this);
+      pairs = getSearchParamPairs(this);
+      i++;
+    }
+  }
+
+  // https://heycam.github.io/webidl/#es-iterable
+  keys() {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+
+    return createSearchParamsIterator(this, 'key');
+  }
+
+  values() {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+
+    return createSearchParamsIterator(this, 'value');
+  }
+
+  // https://url.spec.whatwg.org/#urlsearchparams-stringification-behavior
   toString() {
+    if (!this || !(this instanceof URLSearchParams)) {
+      throw new TypeError('Value of `this` is not a URLSearchParams');
+    }
+
     return querystring.stringify(this[searchParams]);
   }
 }
+// https://heycam.github.io/webidl/#es-iterable-entries
+URLSearchParams.prototype[Symbol.iterator] = URLSearchParams.prototype.entries;
+Object.defineProperty(URLSearchParams.prototype, Symbol.toStringTag, {
+  value: 'URLSearchParamsPrototype',
+  writable: false,
+  enumerable: false,
+  configurable: true
+});
+
+// https://heycam.github.io/webidl/#dfn-default-iterator-object
+function createSearchParamsIterator(target, kind) {
+  const iterator = Object.create(URLSearchParamsIteratorPrototype);
+  iterator[context] = {
+    target,
+    kind,
+    index: 0
+  };
+  return iterator;
+}
+
+// https://heycam.github.io/webidl/#dfn-iterator-prototype-object
+const URLSearchParamsIteratorPrototype = Object.setPrototypeOf({
+  next() {
+    if (!this ||
+        Object.getPrototypeOf(this) !== URLSearchParamsIteratorPrototype) {
+      throw new TypeError('Value of `this` is not a URLSearchParamsIterator');
+    }
+
+    const {
+      target,
+      kind,
+      index
+    } = this[context];
+    const values = getSearchParamPairs(target);
+    const len = values.length;
+    if (index >= len) {
+      return {
+        value: undefined,
+        done: true
+      };
+    }
+
+    const pair = values[index];
+    this[context].index = index + 1;
+
+    let result;
+    if (kind === 'key') {
+      result = pair[0];
+    } else if (kind === 'value') {
+      result = pair[1];
+    } else {
+      result = pair;
+    }
+
+    return {
+      value: result,
+      done: false
+    };
+  }
+}, IteratorPrototype);
+
+// Unlike interface and its prototype object, both default iterator object and
+// iterator prototype object of an interface have the same class string.
+Object.defineProperty(URLSearchParamsIteratorPrototype, Symbol.toStringTag, {
+  value: 'URLSearchParamsIterator',
+  writable: false,
+  enumerable: false,
+  configurable: true
+});
 
 URL.originFor = function(url) {
   if (!(url instanceof URL))

test/parallel/test-whatwg-url-searchparams-append.js

@@ -0,0 +1,52 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Append same name
+params = new URLSearchParams();
+params.append('a', 'b');
+assert.strictEqual(params + '', 'a=b');
+params.append('a', 'b');
+assert.strictEqual(params + '', 'a=b&a=b');
+params.append('a', 'c');
+assert.strictEqual(params + '', 'a=b&a=b&a=c');
+
+// Append empty strings
+params = new URLSearchParams();
+params.append('', '');
+assert.strictEqual(params + '', '=');
+params.append('', '');
+assert.strictEqual(params + '', '=&=');
+
+// Append null
+params = new URLSearchParams();
+params.append(null, null);
+assert.strictEqual(params + '', 'null=null');
+params.append(null, null);
+assert.strictEqual(params + '', 'null=null&null=null');
+
+// Append multiple
+params = new URLSearchParams();
+params.append('first', 1);
+params.append('second', 2);
+params.append('third', '');
+params.append('first', 10);
+assert.strictEqual(true, params.has('first'),
+                   'Search params object has name "first"');
+assert.strictEqual(params.get('first'), '1',
+                   'Search params object has name "first" with value "1"');
+assert.strictEqual(params.get('second'), '2',
+                   'Search params object has name "second" with value "2"');
+assert.strictEqual(params.get('third'), '',
+                   'Search params object has name "third" with value ""');
+params.append('first', 10);
+assert.strictEqual(params.get('first'), '1',
+                   'Search params object has name "first" with value "1"');

test/parallel/test-whatwg-url-searchparams-constructor.js

@@ -0,0 +1,134 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Basic URLSearchParams construction
+params = new URLSearchParams();
+assert.strictEqual(params + '', '');
+params = new URLSearchParams('');
+assert.strictEqual(params + '', '');
+params = new URLSearchParams('a=b');
+assert.strictEqual(params + '', 'a=b');
+params = new URLSearchParams(params);
+assert.strictEqual(params + '', 'a=b');
+
+// URLSearchParams constructor, empty.
+assert.throws(() => URLSearchParams(), TypeError,
+              'Calling \'URLSearchParams\' without \'new\' should throw.');
+// assert.throws(() => new URLSearchParams(DOMException.prototype), TypeError);
+assert.throws(() => {
+  new URLSearchParams({
+    toString() { throw new TypeError('Illegal invocation'); }
+  });
+}, TypeError);
+params = new URLSearchParams('');
+assert.notEqual(params, null, 'constructor returned non-null value.');
+// eslint-disable-next-line no-proto
+assert.strictEqual(params.__proto__, URLSearchParams.prototype,
+                   'expected URLSearchParams.prototype as prototype.');
+params = new URLSearchParams({});
+// assert.strictEqual(params + '', '%5Bobject+Object%5D=');
+assert.strictEqual(params + '', '%5Bobject%20Object%5D=');
+
+// URLSearchParams constructor, string.
+params = new URLSearchParams('a=b');
+assert.notEqual(params, null, 'constructor returned non-null value.');
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(false, params.has('b'),
+                   'Search params object has not got name "b"');
+params = new URLSearchParams('a=b&c');
+assert.notEqual(params, null, 'constructor returned non-null value.');
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(true, params.has('c'),
+                   'Search params object has name "c"');
+params = new URLSearchParams('&a&&& &&&&&a+b=& c&m%c3%b8%c3%b8');
+assert.notEqual(params, null, 'constructor returned non-null value.');
+assert.strictEqual(true, params.has('a'), 'Search params object has name "a"');
+assert.strictEqual(true, params.has('a b'),
+                   'Search params object has name "a b"');
+assert.strictEqual(true, params.has(' '),
+                   'Search params object has name " "');
+assert.strictEqual(false, params.has('c'),
+                   'Search params object did not have the name "c"');
+assert.strictEqual(true, params.has(' c'),
+                   'Search params object has name " c"');
+assert.strictEqual(true, params.has('møø'),
+                   'Search params object has name "møø"');
+
+// URLSearchParams constructor, object.
+const seed = new URLSearchParams('a=b&c=d');
+params = new URLSearchParams(seed);
+assert.notEqual(params, null, 'constructor returned non-null value.');
+assert.strictEqual(params.get('a'), 'b');
+assert.strictEqual(params.get('c'), 'd');
+assert.strictEqual(false, params.has('d'));
+// The name-value pairs are copied when created; later updates
+// should not be observable.
+seed.append('e', 'f');
+assert.strictEqual(false, params.has('e'));
+params.append('g', 'h');
+assert.strictEqual(false, seed.has('g'));
+
+// Parse +
+params = new URLSearchParams('a=b+c');
+assert.strictEqual(params.get('a'), 'b c');
+params = new URLSearchParams('a+b=c');
+assert.strictEqual(params.get('a b'), 'c');
+
+// Parse space
+params = new URLSearchParams('a=b c');
+assert.strictEqual(params.get('a'), 'b c');
+params = new URLSearchParams('a b=c');
+assert.strictEqual(params.get('a b'), 'c');
+
+// Parse %20
+params = new URLSearchParams('a=b%20c');
+assert.strictEqual(params.get('a'), 'b c');
+params = new URLSearchParams('a%20b=c');
+assert.strictEqual(params.get('a b'), 'c');
+
+// Parse \0
+params = new URLSearchParams('a=b\0c');
+assert.strictEqual(params.get('a'), 'b\0c');
+params = new URLSearchParams('a\0b=c');
+assert.strictEqual(params.get('a\0b'), 'c');
+
+// Parse %00
+params = new URLSearchParams('a=b%00c');
+assert.strictEqual(params.get('a'), 'b\0c');
+params = new URLSearchParams('a%00b=c');
+assert.strictEqual(params.get('a\0b'), 'c');
+
+// Parse \u2384 (Unicode Character 'COMPOSITION SYMBOL' (U+2384))
+params = new URLSearchParams('a=b\u2384');
+assert.strictEqual(params.get('a'), 'b\u2384');
+params = new URLSearchParams('a\u2384b=c');
+assert.strictEqual(params.get('a\u2384b'), 'c');
+
+// Parse %e2%8e%84 (Unicode Character 'COMPOSITION SYMBOL' (U+2384))
+params = new URLSearchParams('a=b%e2%8e%84');
+assert.strictEqual(params.get('a'), 'b\u2384');
+params = new URLSearchParams('a%e2%8e%84b=c');
+assert.strictEqual(params.get('a\u2384b'), 'c');
+
+// Parse \uD83D\uDCA9 (Unicode Character 'PILE OF POO' (U+1F4A9))
+params = new URLSearchParams('a=b\uD83D\uDCA9c');
+assert.strictEqual(params.get('a'), 'b\uD83D\uDCA9c');
+params = new URLSearchParams('a\uD83D\uDCA9b=c');
+assert.strictEqual(params.get('a\uD83D\uDCA9b'), 'c');
+
+// Parse %f0%9f%92%a9 (Unicode Character 'PILE OF POO' (U+1F4A9))
+params = new URLSearchParams('a=b%f0%9f%92%a9c');
+assert.strictEqual(params.get('a'), 'b\uD83D\uDCA9c');
+params = new URLSearchParams('a%f0%9f%92%a9b=c');
+assert.strictEqual(params.get('a\uD83D\uDCA9b'), 'c');

test/parallel/test-whatwg-url-searchparams-delete.js

@@ -0,0 +1,44 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Delete basics
+params = new URLSearchParams('a=b&c=d');
+params.delete('a');
+assert.strictEqual(params + '', 'c=d');
+params = new URLSearchParams('a=a&b=b&a=a&c=c');
+params.delete('a');
+assert.strictEqual(params + '', 'b=b&c=c');
+params = new URLSearchParams('a=a&=&b=b&c=c');
+params.delete('');
+assert.strictEqual(params + '', 'a=a&b=b&c=c');
+params = new URLSearchParams('a=a&null=null&b=b');
+params.delete(null);
+assert.strictEqual(params + '', 'a=a&b=b');
+params = new URLSearchParams('a=a&undefined=undefined&b=b');
+params.delete(undefined);
+assert.strictEqual(params + '', 'a=a&b=b');
+
+// Deleting appended multiple
+params = new URLSearchParams();
+params.append('first', 1);
+assert.strictEqual(true, params.has('first'),
+                   'Search params object has name "first"');
+assert.strictEqual(params.get('first'), '1',
+                   'Search params object has name "first" with value "1"');
+params.delete('first');
+assert.strictEqual(false, params.has('first'),
+                   'Search params object has no "first" name');
+params.append('first', 1);
+params.append('first', 10);
+params.delete('first');
+assert.strictEqual(false, params.has('first'),
+                   'Search params object has no "first" name');

test/parallel/test-whatwg-url-searchparams-foreach.js

@@ -0,0 +1,43 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+let a, b, i;
+
+// ForEach Check
+params = new URLSearchParams('a=1&b=2&c=3');
+const keys = [];
+const values = [];
+params.forEach(function(value, key) {
+  keys.push(key);
+  values.push(value);
+});
+assert.deepStrictEqual(keys, ['a', 'b', 'c']);
+assert.deepStrictEqual(values, ['1', '2', '3']);
+
+// For-of Check
+a = new URL('http://a.b/c?a=1&b=2&c=3&d=4');
+b = a.searchParams;
+const c = [];
+for (i of b) {
+  a.search = 'x=1&y=2&z=3';
+  c.push(i);
+}
+assert.deepStrictEqual(c[0], ['a', '1']);
+assert.deepStrictEqual(c[1], ['y', '2']);
+assert.deepStrictEqual(c[2], ['z', '3']);
+
+// empty
+a = new URL('http://a.b/c');
+b = a.searchParams;
+for (i of b) {
+  assert(false, 'should not be reached');
+}

test/parallel/test-whatwg-url-searchparams-get.js

@@ -0,0 +1,35 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Get basics
+params = new URLSearchParams('a=b&c=d');
+assert.strictEqual(params.get('a'), 'b');
+assert.strictEqual(params.get('c'), 'd');
+assert.strictEqual(params.get('e'), null);
+params = new URLSearchParams('a=b&c=d&a=e');
+assert.strictEqual(params.get('a'), 'b');
+params = new URLSearchParams('=b&c=d');
+assert.strictEqual(params.get(''), 'b');
+params = new URLSearchParams('a=&c=d&a=e');
+assert.strictEqual(params.get('a'), '');
+
+// More get() basics
+params = new URLSearchParams('first=second&third&&');
+assert.notEqual(params, null, 'constructor returned non-null value.');
+assert.strictEqual(true, params.has('first'),
+                   'Search params object has name "first"');
+assert.strictEqual(params.get('first'), 'second',
+                   'Search params object has name "first" with value "second"');
+assert.strictEqual(params.get('third'), '',
+                   'Search params object has name "third" with empty value.');
+assert.strictEqual(params.get('fourth'), null,
+                   'Search params object has no "fourth" name and value.');

test/parallel/test-whatwg-url-searchparams-getall.js

@@ -0,0 +1,43 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+let matches;
+
+// getAll() basics
+params = new URLSearchParams('a=b&c=d');
+assert.deepStrictEqual(params.getAll('a'), ['b']);
+assert.deepStrictEqual(params.getAll('c'), ['d']);
+assert.deepStrictEqual(params.getAll('e'), []);
+params = new URLSearchParams('a=b&c=d&a=e');
+assert.deepStrictEqual(params.getAll('a'), ['b', 'e']);
+params = new URLSearchParams('=b&c=d');
+assert.deepStrictEqual(params.getAll(''), ['b']);
+params = new URLSearchParams('a=&c=d&a=e');
+assert.deepStrictEqual(params.getAll('a'), ['', 'e']);
+
+// getAll() multiples
+params = new URLSearchParams('a=1&a=2&a=3&a');
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+matches = params.getAll('a');
+assert(matches && matches.length == 4,
+       'Search params object has values for name "a"');
+assert.deepStrictEqual(matches, ['1', '2', '3', ''],
+                       'Search params object has expected name "a" values');
+params.set('a', 'one');
+assert.strictEqual(params.get('a'), 'one',
+                   'Search params object has name "a" with value "one"');
+matches = params.getAll('a');
+assert(matches && matches.length == 1,
+       'Search params object has values for name "a"');
+assert.deepStrictEqual(matches, ['one'],
+                       'Search params object has expected name "a" values');

test/parallel/test-whatwg-url-searchparams-has.js

@@ -0,0 +1,39 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Has basics
+params = new URLSearchParams('a=b&c=d');
+assert.strictEqual(true, params.has('a'));
+assert.strictEqual(true, params.has('c'));
+assert.strictEqual(false, params.has('e'));
+params = new URLSearchParams('a=b&c=d&a=e');
+assert.strictEqual(true, params.has('a'));
+params = new URLSearchParams('=b&c=d');
+assert.strictEqual(true, params.has(''));
+params = new URLSearchParams('null=a');
+assert.strictEqual(true, params.has(null));
+
+// has() following delete()
+params = new URLSearchParams('a=b&c=d&&');
+params.append('first', 1);
+params.append('first', 2);
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(true, params.has('c'),
+                   'Search params object has name "c"');
+assert.strictEqual(true, params.has('first'),
+                   'Search params object has name "first"');
+assert.strictEqual(false, params.has('d'),
+                   'Search params object has no name "d"');
+params.delete('first');
+assert.strictEqual(false, params.has('first'),
+                   'Search params object has no name "first"');

test/parallel/test-whatwg-url-searchparams-set.js

@@ -0,0 +1,38 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Set basics
+params = new URLSearchParams('a=b&c=d');
+params.set('a', 'B');
+assert.strictEqual(params + '', 'a=B&c=d');
+params = new URLSearchParams('a=b&c=d&a=e');
+params.set('a', 'B');
+assert.strictEqual(params + '', 'a=B&c=d');
+params.set('e', 'f');
+assert.strictEqual(params + '', 'a=B&c=d&e=f');
+
+// URLSearchParams.set
+params = new URLSearchParams('a=1&a=2&a=3');
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(params.get('a'), '1',
+                   'Search params object has name "a" with value "1"');
+params.set('first', 4);
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(params.get('a'), '1',
+                   'Search params object has name "a" with value "1"');
+params.set('a', 4);
+assert.strictEqual(true, params.has('a'),
+                   'Search params object has name "a"');
+assert.strictEqual(params.get('a'), '4',
+                   'Search params object has name "a" with value "4"');

test/parallel/test-whatwg-url-searchparams-stringifier.js

@@ -0,0 +1,116 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const URL = require('url').URL;
+
+const m = new URL('http://example.org');
+let params = m.searchParams;
+
+// Until we export URLSearchParams
+const URLSearchParams = params.constructor;
+
+// Serialize space
+// querystring does not currently handle spaces intelligently
+// params = new URLSearchParams();
+// params.append('a', 'b c');
+// assert.strictEqual(params + '', 'a=b+c');
+// params.delete('a');
+// params.append('a b', 'c');
+// assert.strictEqual(params + '', 'a+b=c');
+
+// Serialize empty value
+params = new URLSearchParams();
+params.append('a', '');
+assert.strictEqual(params + '', 'a=');
+params.append('a', '');
+assert.strictEqual(params + '', 'a=&a=');
+params.append('', 'b');
+assert.strictEqual(params + '', 'a=&a=&=b');
+params.append('', '');
+assert.strictEqual(params + '', 'a=&a=&=b&=');
+params.append('', '');
+assert.strictEqual(params + '', 'a=&a=&=b&=&=');
+
+// Serialize empty name
+params = new URLSearchParams();
+params.append('', 'b');
+assert.strictEqual(params + '', '=b');
+params.append('', 'b');
+assert.strictEqual(params + '', '=b&=b');
+
+// Serialize empty name and value
+params = new URLSearchParams();
+params.append('', '');
+assert.strictEqual(params + '', '=');
+params.append('', '');
+assert.strictEqual(params + '', '=&=');
+
+// Serialize +
+params = new URLSearchParams();
+params.append('a', 'b+c');
+assert.strictEqual(params + '', 'a=b%2Bc');
+params.delete('a');
+params.append('a+b', 'c');
+assert.strictEqual(params + '', 'a%2Bb=c');
+
+// Serialize =
+params = new URLSearchParams();
+params.append('=', 'a');
+assert.strictEqual(params + '', '%3D=a');
+params.append('b', '=');
+assert.strictEqual(params + '', '%3D=a&b=%3D');
+
+// Serialize &
+params = new URLSearchParams();
+params.append('&', 'a');
+assert.strictEqual(params + '', '%26=a');
+params.append('b', '&');
+assert.strictEqual(params + '', '%26=a&b=%26');
+
+// Serialize *-._
+params = new URLSearchParams();
+params.append('a', '*-._');
+assert.strictEqual(params + '', 'a=*-._');
+params.delete('a');
+params.append('*-._', 'c');
+assert.strictEqual(params + '', '*-._=c');
+
+// Serialize %
+params = new URLSearchParams();
+params.append('a', 'b%c');
+assert.strictEqual(params + '', 'a=b%25c');
+params.delete('a');
+params.append('a%b', 'c');
+assert.strictEqual(params + '', 'a%25b=c');
+
+// Serialize \\0
+params = new URLSearchParams();
+params.append('a', 'b\0c');
+assert.strictEqual(params + '', 'a=b%00c');
+params.delete('a');
+params.append('a\0b', 'c');
+assert.strictEqual(params + '', 'a%00b=c');
+
+// Serialize \uD83D\uDCA9
+// Unicode Character 'PILE OF POO' (U+1F4A9)
+params = new URLSearchParams();
+params.append('a', 'b\uD83D\uDCA9c');
+assert.strictEqual(params + '', 'a=b%F0%9F%92%A9c');
+params.delete('a');
+params.append('a\uD83D\uDCA9b', 'c');
+assert.strictEqual(params + '', 'a%F0%9F%92%A9b=c');
+
+// URLSearchParams.toString
+
+// querystring parses `&&` as {'': ''}
+// params = new URLSearchParams('a=b&c=d&&e&&');
+// assert.strictEqual(params.toString(), 'a=b&c=d&e=');
+
+// querystring does not currently handle spaces intelligently
+// params = new URLSearchParams('a = b &a=b&c=d%20');
+// assert.strictEqual(params.toString(), 'a+=+b+&a=b&c=d+');
+
+// The lone '=' _does_ survive the roundtrip.
+params = new URLSearchParams('a=&a=b');
+assert.strictEqual(params.toString(), 'a=&a=b');

test/parallel/test-whatwg-url-searchparams.js

@@ -29,8 +29,21 @@ assert.strictEqual(sp.toString(), serialized);
 
 assert.strictEqual(m.search, `?${serialized}`);
 
+assert.strictEqual(sp[Symbol.iterator], sp.entries);
+
 var key, val, n = 0;
 for ([key, val] of sp) {
   assert.strictEqual(key, 'a');
   assert.strictEqual(val, String(values[n++]));
 }
+n = 0;
+for (key of sp.keys()) {
+  assert.strictEqual(key, 'a');
+}
+n = 0;
+for (val of sp.values()) {
+  assert.strictEqual(val, String(values[n++]));
+}
+
+m.search = '?a=a&b=b';
+assert.strictEqual(sp.toString(), 'a=a&b=b');