Iterator join proposal

Author: slowcheetah

docs/web/docs/features/proposals/iterator-join.md

@@ -0,0 +1,28 @@
+# Iterator join
+[Specification](https://bakkot.github.io/proposal-iterator-join/)\
+[Proposal repo](https://github.com/bakkot/proposal-iterator-join)
+
+## Modules
+[`esnext.iterator.join`](https://github.com/zloirock/core-js/blob/v4/packages/core-js/modules/esnext.iterator.join.js)
+
+## Built-ins signatures
+```ts
+class Iterator {
+  join(separator?: string | undefined): string;
+}
+```
+
+## [Entry points]({docs-version}/docs/usage#h-entry-points)
+```ts
+core-js/proposals/iterator-join
+core-js(-pure)/full/iterator/join
+```
+
+## Examples
+```js
+const digits = () => [1, 2, 3].values();
+digits().join();  // => '1,2,3'
+
+const words = () => ['Hello', 'core-js'].values();
+words().join(' ');  // => 'Hello core-js'
+```

docs/web/docs/menu.json

@@ -341,6 +341,10 @@
               {
                 "title": "Function.prototype.demethodize",
                 "url": "{docs-version}/docs/features/proposals/function-prototype-demethodize"
+              },
+              {
+                "title": "Iterator join",
+                "url": "{docs-version}/docs/features/proposals/iterator-join"
               }
             ]
           }

packages/core-js-compat/src/data.mjs

@@ -2347,6 +2347,8 @@ export const data = {
   },
   'esnext.iterator.concat': {
   },
+  'esnext.iterator.join': {
+  },
   'esnext.iterator.range': {
   },
   'esnext.iterator.to-async': {

packages/core-js-pure/package.json

@@ -582,6 +582,8 @@
     "./proposals/iterator-helpers.js": "./proposals/iterator-helpers.js",
     "./proposals/iterator-chunking": "./proposals/iterator-chunking.js",
     "./proposals/iterator-chunking.js": "./proposals/iterator-chunking.js",
+    "./proposals/iterator-join": "./proposals/iterator-join.js",
+    "./proposals/iterator-join.js": "./proposals/iterator-join.js",
     "./proposals/iterator-range": "./proposals/iterator-range.js",
     "./proposals/iterator-range.js": "./proposals/iterator-range.js",
     "./proposals/iterator-sequencing": "./proposals/iterator-sequencing.js",

packages/core-js/modules/esnext.iterator.join.js

@@ -0,0 +1,39 @@
+'use strict';
+var $ = require('../internals/export');
+var $toString = require('../internals/to-string');
+var anObject = require('../internals/an-object');
+var getIteratorDirect = require('../internals/get-iterator-direct');
+var isNullOrUndefined = require('../internals/is-null-or-undefined');
+var iterate = require('../internals/iterate');
+var iteratorClose = require('../internals/iterator-close');
+var uncurryThis = require('../internals/function-uncurry-this');
+
+var stringConcat = uncurryThis(''.concat);
+
+// `Iterator.prototype.join` method
+// https://bakkot.github.io/proposal-iterator-join/
+// dependency: es.iterator.constructor
+$({ target: 'Iterator', proto: true, real: true, forced: true }, {
+  join: function join(separator) {
+    var O = anObject(this);
+    var sep;
+    try {
+      sep = separator === undefined ? ',' : $toString(separator);
+    } catch (error) {
+      iteratorClose(O, 'throw', error);
+    }
+    var first = true;
+    var result = '';
+    var iterated = getIteratorDirect(O);
+    iterate(iterated, function (value) {
+      if (first) {
+        first = false;
+      } else {
+        result = stringConcat(result, sep);
+      }
+      if (isNullOrUndefined(value)) return;
+      result = stringConcat(result, $toString(value));
+    }, { IS_RECORD: true });
+    return result;
+  },
+});

packages/core-js/package.json

@@ -576,6 +576,8 @@
     "./proposals/iterator-helpers.js": "./proposals/iterator-helpers.js",
     "./proposals/iterator-chunking": "./proposals/iterator-chunking.js",
     "./proposals/iterator-chunking.js": "./proposals/iterator-chunking.js",
+    "./proposals/iterator-join": "./proposals/iterator-join.js",
+    "./proposals/iterator-join.js": "./proposals/iterator-join.js",
     "./proposals/iterator-range": "./proposals/iterator-range.js",
     "./proposals/iterator-range.js": "./proposals/iterator-range.js",
     "./proposals/iterator-sequencing": "./proposals/iterator-sequencing.js",

scripts/build-entries/entries-definitions.mjs

@@ -1306,6 +1306,12 @@ export const features = {
     namespace: 'Iterator',
     name: 'forEach',
   },
+  'iterator/join': {
+    modules: ['esnext.iterator.join'],
+    template: $uncurried,
+    namespace: 'Iterator',
+    name: 'join',
+  },
   'iterator/map': {
     modules: ['es.iterator.map'],
     template: $uncurried,
@@ -3457,6 +3463,13 @@ export const proposals = {
       'esnext.iterator.windows',
     ],
   },
+  'iterator-join': {
+    link: 'https://github.com/bakkot/proposal-iterator-join',
+    stage: 0,
+    modules: [
+      'esnext.iterator.join',
+    ],
+  },
   'iterator-range': {
     link: 'https://github.com/tc39/proposal-Number.range',
     stage: 2,

tests/babel-plugin/fixtures/entry-global/import-full-chrome-135-v4.0/output.mjs

@@ -33,6 +33,7 @@ import "core-js/modules/esnext.function.demethodize";
 import "core-js/modules/esnext.function.metadata";
 import "core-js/modules/esnext.iterator.chunks";
 import "core-js/modules/esnext.iterator.concat";
+import "core-js/modules/esnext.iterator.join";
 import "core-js/modules/esnext.iterator.range";
 import "core-js/modules/esnext.iterator.to-async";
 import "core-js/modules/esnext.iterator.windows";

tests/babel-plugin/fixtures/entry-global/import-full-chrome-135-v4.999/output.mjs

@@ -33,6 +33,7 @@ import "core-js/modules/esnext.function.demethodize";
 import "core-js/modules/esnext.function.metadata";
 import "core-js/modules/esnext.iterator.chunks";
 import "core-js/modules/esnext.iterator.concat";
+import "core-js/modules/esnext.iterator.join";
 import "core-js/modules/esnext.iterator.range";
 import "core-js/modules/esnext.iterator.to-async";
 import "core-js/modules/esnext.iterator.windows";

tests/babel-plugin/fixtures/entry-global/import-full-ie11-v4.0/output.mjs

@@ -299,6 +299,7 @@ import "core-js/modules/esnext.function.demethodize";
 import "core-js/modules/esnext.function.metadata";
 import "core-js/modules/esnext.iterator.chunks";
 import "core-js/modules/esnext.iterator.concat";
+import "core-js/modules/esnext.iterator.join";
 import "core-js/modules/esnext.iterator.range";
 import "core-js/modules/esnext.iterator.to-async";
 import "core-js/modules/esnext.iterator.windows";