Error Stack Column number

[Sundararajan Athijegannathan]

Error has columnNumber property - but as you've noted it is not always
available :(  If the error is thrown from script code anywhere via
ECMAScript throw statement, we do populate column number - because
nashorn could compile the code appropriately to put column number! 

But, there are places in nashorn runtime code where ECMAScript errors
are thrown. For example, RangeError thrown from deep inside nashorn
runtime Java code! From those places, we can only recover java stack
trace & populate properties of ECMA error object.  As java
StackTraceElement objects do not have column number, we can't populate
column number.

-Sundar

On 12/2/2016 2:06 PM, Art Fiedler wrote:
> Your right it's still not standard even in the EMCAScript 2016, it just
> seems to
> be the commonality. When thinking java yes line only makes sense as
> typically
> one who writes java does not minify the code. When thinking javascript
> however
> minified code is quite normal and myfile:1 might mean 5000 other lines as
> well.
>
> I looked into the source some to see if it actually is feasible to build my
> own
> stacktrace with file:line:column, however in the current state it seems
> impossible! Nashorn actually uses java.lang.Throwable.getStackTrace() to
> get the
> stack and that ends up being native. The only place you can get the
> columnNumber
> is for the specific location the error was thrown. Keyword "thrown".
>
> If you noticed my previous sample new Error().columnNumber === -1 since
> columnNumber is not populated... however if you throw & catch then...
>     try { throw new Error(); }
>     catch(e) { /* e.columnNumber === 6 */ }
>
> In my case with console.count(), the need for columnNumber is not the
> location
> of new Error() either, since the console.count() function would need the
> callers file:line:col as that is where console.count() is called from.
>
> In the end I still think if the stack element is from a script it should
> include
> the column number like node.js, ff, edge all seem to be doing. Since a line
> only
> is useless when the script is minified. However considering that nashorn is
> not
> providing the stackTrace directly, I could see why the team may not want to
> include the columnNumber. If you do however know of another way to get the
> callers file:line:col please let me know. My second thought was to check
> arguments.callee.caller for that info but no dice.
>
> -Arthur Fiedler
>
> We do not aim to provide complete compatibility with other JS
>> implementations on the non-standard properties such as "stack". stack
>> tries to mimic whatever is done for Java code (no column number for
>> eg.). But, as you've noted there are enough information on Error objects
>> via other properties like lineNumber, columnNumber, fileName. It should
>> be possible to write a simple utility function to format stack string as
>> desired for specific applications.
>>
>> Thanks,
>> -Sundar
>>