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Add for-of fallback for arrays in browsers without symbol support #11263

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merged 4 commits into from Mar 19, 2020
Merged

Add for-of fallback for arrays in browsers without symbol support #11263

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490f4ea
Add for-of fallback for arrays in browsers without symbol support
nicolo-ribaudo Mar 14, 2020
fe088fe
Update after rebase
nicolo-ribaudo Mar 17, 2020
f36c9f5
Re-throw error when iterating array
nicolo-ribaudo Mar 19, 2020
2205820
Update fixture
nicolo-ribaudo Mar 19, 2020
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19 changes: 18 additions & 1 deletion packages/babel-helpers/src/helpers.js
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Expand Up @@ -1043,8 +1043,24 @@ helpers.createForOfIteratorHelper = helper("7.9.0")`
// f: finish (always called at the end)

export default function _createForOfIteratorHelper(o) {
if (typeof Symbol === "undefined" || o[Symbol.iterator] == null)
if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) {
// Fallback for engines without symbol support
if (Array.isArray(o)) {
var i = 0;
var F = function(){};
return {
s: F,
n: function() {
if (i >= o.length) return { done: true };
return { done: false, value: o[i++] };
},
e: F,
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This e method needs to throw the passed in error.

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Thanks, good catch!

f: F,
};
}

throw new TypeError("Invalid attempt to iterate non-iterable instance.\\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method.");
}

var it, normalCompletion = true, didErr = false, err;

Expand Down Expand Up @@ -1077,6 +1093,7 @@ helpers.createForOfIteratorHelperLoose = helper("7.9.0")`
var i = 0;

if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) {
// Fallback for engines without symbol support
if (Array.isArray(o))
return function() {
if (i >= o.length) return { done: true };
Expand Down
2 changes: 1 addition & 1 deletion packages/babel-preset-env/test/fixtures/sanity/block-scoping-for-of/output.js
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Expand Up @@ -6,7 +6,7 @@ function _iterableToArrayLimit(arr, i) { if ((typeof Symbol === "undefined" || !

function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }

function _createForOfIteratorHelper(o) { if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); var it, normalCompletion = true, didErr = false, err; return { s: function s() { it = o[Symbol.iterator](); }, n: function n() { var step = it.next(); normalCompletion = step.done; return step; }, e: function e(_e) { didErr = true; err = _e; }, f: function f() { try { if (!normalCompletion && it["return"] != null) it["return"](); } finally { if (didErr) throw err; } } }; }
function _createForOfIteratorHelper(o) { if (typeof Symbol === "undefined" || o[Symbol.iterator] == null) { if (Array.isArray(o)) { var i = 0; var F = function F() {}; return { s: F, n: function n() { if (i >= o.length) return { done: true }; return { done: false, value: o[i++] }; }, e: F, f: F }; } throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); } var it, normalCompletion = true, didErr = false, err; return { s: function s() { it = o[Symbol.iterator](); }, n: function n() { var step = it.next(); normalCompletion = step.done; return step; }, e: function e(_e) { didErr = true; err = _e; }, f: function f() { try { if (!normalCompletion && it["return"] != null) it["return"](); } finally { if (didErr) throw err; } } }; }

// https://github.com/babel/babel/issues/7557
var _iterator = _createForOfIteratorHelper(c),
Expand Down