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Drop __proto__ keys (#35)
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ninevra authored Apr 7, 2021
1 parent eefcc77 commit ddca73d
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Showing 2 changed files with 12 additions and 8 deletions.
5 changes: 5 additions & 0 deletions index.js
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,11 @@ const mapObject = (object, mapper, options, isSeen = new WeakMap()) => {
for (const [key, value] of Object.entries(object)) {
let [newKey, newValue, {shouldRecurse = true} = {}] = mapper(key, value, object);

// Drop `__proto__` keys.
if (newKey === '__proto__') {
continue;
}

if (options.deep && shouldRecurse && isObjectCustom(newValue)) {
newValue = Array.isArray(newValue) ?
mapArray(newValue) :
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15 changes: 7 additions & 8 deletions test.js
Original file line number Diff line number Diff line change
Expand Up @@ -153,14 +153,13 @@ test('validates input', t => {
}, TypeError);
});

test.failing('identity function preserves __proto__ keys', t => {
test('__proto__ keys are safely dropped', t => {
const input = {['__proto__']: {one: 1}};
t.deepEqual(mapObject(input, (key, value) => [key, value]), input);
});
const output = mapObject(input, (key, value) => [key, value]);
t.deepEqual(output, {});

test.failing('mapper can produce __proto__ keys', t => {
t.deepEqual(
mapObject({proto: {one: 1}}, (key, value) => [`__${key}__`, value]),
{['__proto__']: {one: 1}}
);
// AVA's equality checking isn't quite strict enough to catch the difference
// between plain objects as prototypes and Object.prototype, so we also check
// the prototype by identity
t.is(Object.getPrototypeOf(output), Object.prototype);
});

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