BackTracker

Back track in JS code execution and find where a function was called

In applications which are in development and issues seem to come from seemingly no where such as things being undefined in an abstract tree of code execution, it'd be beneficial for developers to know where these issues are coming from and what steps your code is taking to get to said issues.

How it works

In JavaScript, you can make use of Error stacks to peek back into code execution. This project makes use of Error stacks and analyses individual stack frames and tries it's best to pick apart the scope, absolute path of file, line and column of each frame via regular expressions so that this info is available in code rather than requiring a user to analyse the stack. This can allow for some creative uses in code which were not previously available.

Note

This project is still a work in progress. It's functionality is not guaranteed as the regular expressions used to capture stack details are not fool proof.

Contributing

If you would like to contribute and modify the regular expressions, please open a Pull Request and I will test code changes against a dataset of stack frames including stack frames which you might want to add support for.

Examples

test.js

const BackTracker = require("backtracker").BackTracker;

function epic() {
    console.log("Okay. This is epic.");
    console.log(BackTracker.stack.first()));
}

module.exports = epic;

index.js

const epic = require("./test.js");

function notEpic(pog) {
    console.log(pog);
    epic();
}

notEpic("Not epic at all");

starting index.js logs the following

C:\Users\papi\Documents\GitHub\BackTracker>node example/index.js
Not epic at all
Okay. This is epic.
Caller {
  path: 'C:\\Users\\papi\\Documents\\GitHub\\BackTracker\\example\\index.js',
  dir: 'C:\\Users\\papi\\Documents\\GitHub\\BackTracker\\example',
  filename: 'index.js',
  async: false,
  scope: undefined,
  line: 5,
  column: 2,
  anonymous: false,
  parent: Caller {
    path: 'C:\\Users\\papi\\Documents\\GitHub\\BackTracker\\example\\index.js',
    dir: 'C:\\Users\\papi\\Documents\\GitHub\\BackTracker\\example',
    filename: 'index.js',
    async: false,
    scope: undefined,
    line: 8,
    column: 1,
    anonymous: false,
    parent: Caller {
      path: 'internal/modules/cjs/loader.js',
      dir: 'internal/modules/cjs',
      filename: 'loader.js',
      async: false,
      scope: undefined,
      line: 936,
      column: 30,
      anonymous: false,
      parent: [Caller]
    }
  }
}