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LibJS: Add String.prototype.indexOf position argument

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davidot 2021-06-27 19:14:11 +02:00 • committed by Linus Groh
parent a4c1666b71
commit 36668893a6
2 changed files with 23 additions and 1 deletions
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9
Userland/Libraries/LibJS/Runtime/StringPrototype.cpp
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@ -284,7 +284,14 @@ JS_DEFINE_NATIVE_FUNCTION(StringPrototype::index_of)
auto needle = vm.argument(0).to_string(global_object);
if (vm.exception())
return {};
return Value((i32)string->find(needle).value_or(-1));
size_t from = 0;
if (vm.argument_count() > 1) {
double from_argument = vm.argument(1).to_integer_or_infinity(global_object);
if (vm.exception())
return {};
from = clamp(from_argument, static_cast<double>(0), static_cast<double>(string->length()));
}
return Value((i32)string->find(needle, from).value_or(-1));
}
// 22.1.3.26 String.prototype.toLowerCase ( ), https://tc39.es/ecma262/#sec-string.prototype.tolowercase

15
Userland/Libraries/LibJS/Tests/builtins/String/String.prototype.indexOf.js
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@ -5,4 +5,19 @@ test("basic functionality", () => {
expect(s.indexOf("friends")).toBe(6);
expect(s.indexOf("enemies")).toBe(-1);
expect(s.indexOf("friends", 0)).toBe(6);
expect(s.indexOf("enemies", 0)).toBe(-1);
expect(s.indexOf("friends", 4)).toBe(6);
expect(s.indexOf("friends", 6)).toBe(6);
expect(s.indexOf("friends", 7)).toBe(-1);
expect(s.indexOf("friends", 8)).toBe(-1);
expect(s.indexOf("enemies", 2)).toBe(-1);
expect(s.indexOf("enemies", 7)).toBe(-1);
expect(s.indexOf("e")).toBe(1);
expect(s.indexOf("e", 0)).toBe(1);
expect(s.indexOf("e", 2)).toBe(9);
});