On Mon, Nov 16, 2015 at 5:47 PM, Arthur O'Dwyer
<[email protected]> wrote:
> On Thursday, April 14, 2011 at 12:23:46 AM UTC-7, crtmpserver wrote:
[SNIP]
> Four years later, I have the same question.
> It seems inconceivable that V8 wouldn't know the type of the value
> internally; I'm just trying to get at that type through V8's C++ API.
>
> The two questions behind my question, in case anyone can help with these,
> are:
>
> (1) I'm trying to stringize an arbitrary Javascript object — if it's
> JSONable I'd like to JSON.stringify it, but if that throws, I'd at least
> like to be able to say what type it was. For example, "unserializable object
> of type RegExp" or "unserializable object of type Bicycle" or whatever.
What's the question? Have to use the Value->IsXXXX() methods to
detect the type. No way around it.
long long getType( const v8::FunctionCallbackInfo<v8::Value>& args )
{
if( args[0]->IsUndefined() ) return( 1 << 0 );
if( args[0]->IsNull() ) return( 1 << 1 );
if( args[0]->IsTrue() ) return( 1 << 2 );
if( args[0]->IsFalse() ) return( 1 << 3 );
if( args[0]->IsName() ) return( 1 << 4 );
if( args[0]->IsString() ) return( 1 << 5 );
if( args[0]->IsSymbol() ) return( 1 << 6 );
if( args[0]->IsFunction() ) return( 1 << 7 );
if( args[0]->IsArray() ) return( 1 << 8 );
if( args[0]->IsObject() ) return( 1 << 9 );
if( args[0]->IsBoolean() ) return( 1 << 10 );
if( args[0]->IsNumber() ) return( 1 << 11 );
if( args[0]->IsExternal() ) return( 1 << 12 );
if( args[0]->IsInt32() ) return( 1 << 13 );
if( args[0]->IsUint32() ) return( 1 << 14 );
if( args[0]->IsDate() ) return( 1 << 15 );
if( args[0]->IsArgumentsObject() ) return( 1 << 16 );
if( args[0]->IsBooleanObject() ) return( 1 << 17 );
if( args[0]->IsNumberObject() ) return( 1 << 18 );
if( args[0]->IsStringObject() ) return( 1 << 19 );
if( args[0]->IsSymbolObject() ) return( 1 << 20 );
if( args[0]->IsNativeError() ) return( 1 << 21 );
if( args[0]->IsRegExp() ) return( 1 << 22 );
if( args[0]->IsGeneratorFunction() ) return( 1 << 23 );
if( args[0]->IsGeneratorObject() ) return( 1 << 24 );
if( args[0]->IsPromise() ) return( 1 << 25 );
if( args[0]->IsMap() ) return( 1 << 26 );
if( args[0]->IsSet() ) return( 1 << 27 );
if( args[0]->IsMapIterator() ) return( 1 << 28 );
if( args[0]->IsSetIterator() ) return( 1 << 29 );
if( args[0]->IsWeakMap() ) return( 1 << 30 );
if( args[0]->IsWeakSet() ) return( 1 << 31 );
if( args[0]->IsArrayBuffer() ) return( 1 << 32 );
if( args[0]->IsArrayBufferView() ) return( 1 << 33 );
if( args[0]->IsTypedArray() ) return( 1 << 34 );
if( args[0]->IsUint8Array() ) return( 1 << 35 );
if( args[0]->IsUint8ClampedArray() ) return( 1 << 36 );
if( args[0]->IsInt8Array() ) return( 1 << 37 );
if( args[0]->IsUint16Array() ) return( 1 << 38 );
if( args[0]->IsInt16Array() ) return( 1 << 39 );
if( args[0]->IsUint32Array() ) return( 1 << 40 );
if( args[0]->IsInt32Array() ) return( 1 << 41 );
if( args[0]->IsFloat32Array() ) return( 1 << 42 );
if( args[0]->IsFloat64Array() ) return( 1 << 43 );
if( args[0]->IsFloat32x4() ) return( 1 << 44 );
if( args[0]->IsDataView() ) return( 1 << 45 );
if( args[0]->IsSharedArrayBuffer() ) return( 1 << 46 );
return( 0 );
}
> (2) I'm trying to expose a C++ function into Javascript. My callback is
> defined as
>
> void foo(const v8::FunctionCallbackInfo<v8::Value>& args)
> {
> if (args.Length() != 1) throw "expected a single numeric argument";
> if (args[0]->IsNumber()) throw "expected a single numeric argument";
> // now do something with the numeric value we got
> }
>
> However, the above doesn't seem to accept values that aren't numeric
> literals, e.g.
>
> var x = 42;
> foo(x); // throws because x apparently isn't IsNumber??
>
> If there were a simple way to ask V8 "okay, so it's not IsNumber... what is
> it, then?", then I would have debugged this issue by now.
Your logic is not right.
void foo(const v8::FunctionCallbackInfo<v8::Value>& args)
{
if (args.Length() != 1) throw "expected a single numeric argument";
if (!(args[0]->IsNumber())) throw "expected a single numeric argument";
// now do something with the numeric value we got
}
You could also try
void foo(const v8::FunctionCallbackInfo<v8::Value>& args)
{
if (args.Length() != 1) throw "expected a single numeric argument";
if (!(args[0]->IsNumber()) && !(args[0]->IsInt32()) &&
!(args[0]->IsUint32())) throw "expected a single numeric argument";
// now do something with the numeric value we got
}
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