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LibJS: Allow setting the length of an object with prototype Array

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Before this it would always go through the native setter thus
 modifying the array but now you can set length to anything
This commit is contained in:
davidot 2021-06-25 16:57:12 +02:00 committed by Linus Groh
parent b38fb418f8
commit b1441a47b1
Notes: sideshowbarker 2024-07-18 11:28:44 +09:00 
Author: https://github.com/davidot
Commit: https://github.com/SerenityOS/serenity/commit/b1441a47b16
Pull-request: https://github.com/SerenityOS/serenity/pull/8245
2 changed files with 92 additions and 7 deletions
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39
Userland/Libraries/LibJS/Runtime/Array.cpp
View File

@ -65,25 +65,50 @@ Array* Array::typed_this(VM& vm, GlobalObject& global_object)
JS_DEFINE_NATIVE_GETTER(Array::length_getter)
{
auto* array = typed_this(vm, global_object);
if (!array)
auto* this_object = vm.this_value(global_object).to_object(global_object);
if (!this_object)
return {};
return Value(array->indexed_properties().array_like_size());
// TODO: could be incorrect if receiver/this_value is fixed or changed
if (!this_object->is_array()) {
Value val = this_object->get_own_property(vm.names.length.to_string_or_symbol(), this_object);
if (vm.exception())
return {};
return val;
}
return Value(this_object->indexed_properties().array_like_size());
}
JS_DEFINE_NATIVE_SETTER(Array::length_setter)
{
auto* array = typed_this(vm, global_object);
if (!array)
auto* this_object = vm.this_value(global_object).to_object(global_object);
if (!this_object)
return;
// TODO: could be incorrect if receiver/this_value is fixed or changed
if (!this_object->is_array()) {
this_object->define_property(vm.names.length.to_string_or_symbol(), value, default_attributes);
if (vm.exception())
return;
return;
}
auto length = value.to_number(global_object);
if (vm.exception())
return;
if (length.is_nan() || length.is_infinity() || length.as_double() < 0) {
u32 val = length.as_double();
if (val != length.as_double()
|| length.is_nan()
|| length.is_infinity()
|| length.as_double() < 0
|| length.as_double() > NumericLimits<u32>::max()) {
vm.throw_exception<RangeError>(global_object, ErrorType::InvalidLength, "array");
return;
}
array->indexed_properties().set_array_like_size(length.as_double());
this_object->indexed_properties().set_array_like_size(val);
}
}

60
Userland/Libraries/LibJS/Tests/builtins/Array/array-length-setter.js
View File

@ -55,3 +55,63 @@ describe("normal behavior", () => {
expect(a[1]).toEqual(2);
});
});
describe("behavior when obj has Array prototype", () => {
function ArrExtend() {}
ArrExtend.prototype = [10, 11, 12];
test("Has the properties from prototype", () => {
var arr = new ArrExtend();
expect(arr.length).toEqual(3);
expect(arr[0]).toEqual(10);
expect(arr[1]).toEqual(11);
expect(arr[2]).toEqual(12);
});
test("Can override length to any value", () => {
[null, "Hello friends :^)", -6, 0].forEach(value => {
var arr = new ArrExtend();
arr.length = value;
expect(arr.length).toEqual(value);
// should not wipe high values
expect(arr[0]).toEqual(10);
expect(arr[1]).toEqual(11);
expect(arr[2]).toEqual(12);
});
});
test("Can call array methods", () => {
var arr = new ArrExtend();
arr.push(1);
expect(arr.length).toEqual(4);
expect(arr[3]).toEqual(1);
});
test("If length overwritten uses that value", () => {
[null, "Hello friends :^)", -6, 0].forEach(value => {
var arr = new ArrExtend();
arr.length = value;
expect(arr.length).toEqual(value);
arr.push(99);
expect(arr.length).toEqual(1);
expect(arr[0]).toEqual(99);
// should not wipe higher value
expect(arr[1]).toEqual(11);
expect(arr[2]).toEqual(12);
arr.push(100);
expect(arr.length).toEqual(2);
expect(arr[1]).toEqual(100);
arr.length = 0;
// should not wipe values since we are not an array
expect(arr[0]).toEqual(99);
expect(arr[1]).toEqual(100);
expect(arr[2]).toEqual(12);
});
});
});