Easy access to the call stack, written in pure JavaScript
npm install tracebackWriting a Node app? Need to know the function backtrace? Don't want to compile C++ code? Use Traceback.
Traceback provides a normal JavaScript array of the execution stack frames. You can see function names, line numbers, and other useful stuff.
Traceback is available from NPM.
$ npm install traceback
example.js
``javascript
var traceback = require('../traceback');
function start() { first() }
function first() { second() }
var second = function() { last() }
function last() {
var stack = traceback();
console.log('I am ' + stack[0].name + ' from file ' + stack[0].file)
for(var i = 1; i <= 3; i++)
console.log(' ' + i + ' above me: ' + stack[i].name + ' at line ' + stack[i].line);
}
start();
`
Output:
I am last from file example.js
1 above me: second at line 5
2 above me: first at line 4
3 above me: start at line 3
Simply calling traceback() gives you the stack, with the current function in position 0.
Stack frame objects have normal V8 [CallSite][callsite] objects as prototypes. All those methods will work. You can also call traceback.raw() to get the exact stack made by V8.
But traceback()'s stack frame objects have convenient attribute names:
* name | The function name
* path | The absolute path of the file defining the function
* file | The basename of the path file ("example.js")this
* line | The line number in the file
* col | The column number in the file
* pos | The byte position in the file
* fun | The function itself
* method | If this function was called as a method, the name it is stored as
* this | The object bound to the label in the functionthis
* type | The type of ; the name of the constructor function (Object, ReadStream, etc.)CallSite
* origin | The that ran eval(), if this frame is an evalthis
* is_top | Boolean indicating whether the function was called with a global
* is_eval | Boolean indicating whether the function comes from an callnew
* is_native | Boolean indicating whether the function is native
* is_ctor | Boolean indicating whether this is a constructor () call
They also work correctly in JSON.stringify().
Tests use [node-tap][tap]. Clone this Git repository, run npm install` and then run the tests through npm:
$ npm test
> traceback@0.3.1 test /Users/jhs/src/traceback
> tap test/
ok test/api.js ...................................... 326/326
ok test/fail.js ....................................... 36/36
ok test/format.js ....................................... 7/7
ok test/readme.js ....................................... 2/2
total ............................................... 371/371
ok
Apache 2.0
[callsite]: http://code.google.com/p/v8/wiki/JavaScriptStackTraceApi
[tap]: https://github.com/isaacs/node-tap