heroku-debug/tmp/node_modules/error-callsites/README.md

debugging plugin for the CLI

# error-callsites

Yet another module for extracting callsites (a.k.a. stack-frames) from
Node.js `Error` objects.

[![Build status](https://travis-ci.org/watson/error-callsites.svg?branch=master)](https://travis-ci.org/watson/error-callsites)
[![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)](https://github.com/feross/standard)

## Installation

```
npm install error-callsites
```

## Usage

```js
var callsites = require('error-callsites')

var err = new Error('foo')
var stack = callsites(err)

console.log('Error occurred on line', stack[0].getLineNumber())
```

## API

The module exposes a single function which expects an `Error` object as
the first arguemnt:

```js
var arr = callsites(err)
```

The function returns an array of callsite objects - one for each frame
in the stack trace.

### Callsite object

Each element in the returned array is a [V8 callsite
object](https://code.google.com/p/v8-wiki/wiki/JavaScriptStackTraceApi#Customizing_stack_traces)
and in turn reponds to the following V8 functions:

- `callsite.getThis()` - returns the value of this
- `callsite.getTypeName()` - returns the type of this as a string. This is the name of the function stored in the constructor field of this, if available, otherwise the object's [[Class]] internal property.
- `callsite.getFunction()` - returns the current function
- `callsite.getFunctionName()` - returns the name of the current function, typically its name property. If a name property is not available an attempt will be made to try to infer a name from the function's context.
- `callsite.getMethodName()` - returns the name of the property of this or one of its prototypes that holds the current function
- `callsite.getFileName()` - if this function was defined in a script returns the name of the script
- `callsite.getLineNumber()` - if this function was defined in a script returns the current line number
- `callsite.getColumnNumber()` - if this function was defined in a script returns the current column number
- `callsite.getEvalOrigin()` - if this function was created using a call to eval returns a CallSite object representing the location where eval was called
- `callsite.isToplevel()` - is this a toplevel invocation, that is, is this the global object?
- `callsite.isEval()` - does this call take place in code defined by a call to eval?
- `callsite.isNative()` - is this call in native V8 code?
- `callsite.isConstructor()` - is this a constructor call?

## License

MIT