js.Value narrowing methods (asString/asNumber/as*Array) fail to compile: undefined expectType/expectTypedArrayOfType

[nazarhussain]

Summary

In js.Value, every type-narrowing method calls self.expectType(...) (or self.expectTypedArrayOfType(...)), but neither helper is defined anywhere in the package. As a result, referencing any of these methods is a hard compile error.

Observed on zapi 2.2.0 (src/js/value.zig).

Affected methods

All of these reference the missing helpers:

• asNumber, asString, asBoolean, asBigInt, asFunction, asObject → call self.expectType(...)
• asInt8Array, asUint8Array, asUint8ClampedArray, asInt16Array, asUint16Array, asInt32Array, asUint32Array, asFloat32Array, asFloat64Array, asBigInt64Array, asBigUint64Array → call self.expectTypedArrayOfType(...)

asArray and asDate are not affected — they use self.val.isArray() / self.val.isDate() directly.

A grep confirms the helpers are referenced but never declared:

$ grep -rnE 'fn expectType\b|fn expectTypedArrayOfType\b' src/
# (no matches)

Compile error

src/js/value.zig:117:17: error: no field or member function named 'expectType' in 'js.value.Value'
        try self.expectType(.string);
                 ^~~~~~~~~~

Minimal reproduction

const js = @import("zapi:zapi").js;

// Referencing any narrowing method triggers the error:
pub fn parse(v: js.Value) !void {
    const s = try v.asString(); // error: no member function named 'expectType'
    _ = s;
}

Expected behavior

The narrowing methods should compile and validate the underlying JS type, returning error.TypeMismatch on a mismatch (as their doc comments state).

Likely fix

Add the missing private helpers to Value, e.g.:

fn expectType(self: Value, expected: napi.value_types.ValueType) !void {
    if ((try self.val.typeof()) != expected) return error.TypeMismatch;
}

fn expectTypedArrayOfType(self: Value, expected: napi.value_types.TypedarrayType) !void {
    if (!(try self.val.isTypedarray())) return error.TypeMismatch;
    const info = try self.val.getTypedarrayInfo();
    if (info.type != expected) return error.TypeMismatch;
}

(Field/method names should be matched to the actual napi API.)

Workaround

Construct the DSL wrapper directly and skip the as* validation, e.g. js.String{ .val = napi_value } instead of value.asString().