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LibJS: Add Array.prototype.lastIndexOf

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This commit is contained in:
Kesse Jones 2020-04-21 20:17:16 -03:00 • committed by Andreas Kling
parent 09138d542d
commit b2305cb67d
3 changed files with 58 additions and 0 deletions
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35
Libraries/LibJS/Runtime/ArrayPrototype.cpp
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@ -55,6 +55,7 @@ ArrayPrototype::ArrayPrototype()
put_native_function("slice", slice, 2);
put_native_function("indexOf", index_of, 1);
put_native_function("reverse", reverse, 0);
put_native_function("lastIndexOf", last_index_of, 1);
put("length", Value(0));
}
@ -365,4 +366,38 @@ Value ArrayPrototype::reverse(Interpreter& interpreter)
return array;
}
Value ArrayPrototype::last_index_of(Interpreter& interpreter)
{
auto* array = array_from(interpreter);
if (!array)
return {};
i32 array_size = static_cast<i32>(array->elements().size());
if (interpreter.argument_count() == 0 || array_size == 0)
return Value(-1);
i32 from_index = 0;
if (interpreter.argument_count() >= 2) {
from_index = interpreter.argument(1).to_number().to_i32();
if (from_index >= array_size)
return Value(-1);
auto negative_min_index = ((array_size - 1) * -1);
if (from_index < negative_min_index)
from_index = 0;
else if (from_index < 0)
from_index = array_size + from_index;
}
auto search_element = interpreter.argument(0);
for (i32 i = array_size - 1; i >= from_index; --i) {
auto& element = array->elements().at(i);
if (typed_eq(interpreter, element, search_element).as_bool())
return Value(i);
}
return Value(-1);
}
}

1
Libraries/LibJS/Runtime/ArrayPrototype.h
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@ -52,5 +52,6 @@ private:
static Value slice(Interpreter&);
static Value index_of(Interpreter&);
static Value reverse(Interpreter&);
static Value last_index_of(Interpreter&);
};
}