callsites

What is callsites?

The callsites npm package provides a way to get call sites of the V8 stack trace API in Node.js. It allows developers to inspect the call stack and retrieve information about the function calls that led to a certain point in the code.

What are callsites's main functionalities?

Getting call sites

This feature allows you to retrieve an array of call sites (stack frames) at the point where callsites() is invoked. Each call site is an object with methods that return information about that call site, such as the file name, line number, and column number.

const callsites = require('callsites');

function foo() {
  const sites = callsites();
  console.log(sites[0].getFileName()); // => '/path/to/file.js'
}

foo();

Inspecting call stack

This feature is used to inspect the call stack and get names of the calling functions. It can be useful for debugging or for understanding the flow of function calls leading up to a certain point.

const callsites = require('callsites');

function foo() {
  bar();
}

function bar() {
  const sites = callsites();
  console.log(sites.map(site => site.getFunctionName() || 'anonymous'));
}

foo();

Other packages similar to callsites

stack-trace

The stack-trace package provides similar functionality to callsites by allowing developers to get stack traces and extract detailed information about each stack frame. It differs in its API and additional features for parsing and formatting stack traces.

error-stack-parser

This package is used to parse and extract stack traces from Error objects. It provides a different API but serves a similar purpose in allowing inspection of the call stack. It focuses more on parsing standardized Error stack strings.

trace

Trace is a package that enhances error stack traces. While it does not provide the same direct API for getting call sites, it offers a way to have long stack traces that can be useful for debugging asynchronous code.

stackman

Stackman is another package that can be used to retrieve and manipulate stack traces. It provides rich stack traces with context and source maps support, which can be more informative than the basic call site information provided by callsites.

README

callsites

Get callsites from the V8 stack trace API

Install

npm install callsites

Usage

import callsites from 'callsites';

function unicorn() {
	console.log(callsites()[0].getFileName());
	//=> '/Users/sindresorhus/dev/callsites/test.js'
}

unicorn();

API

Returns an array of callsite objects with the following methods:

• getThis: Returns the value of this.
• 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.
• getFunction: Returns the current function.
• 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.
• getMethodName: Returns the name of the property of this or one of its prototypes that holds the current function.
• getFileName: If this function was defined in a script returns the name of the script.
• getLineNumber: If this function was defined in a script returns the current line number.
• getColumnNumber: If this function was defined in a script returns the current column number
• getEvalOrigin: If this function was created using a call to eval returns a string representing the location where eval was called.
• isToplevel: Returns true if this is a top-level invocation, that is, if it's a global object.
• isEval: Returns true if this call takes place in code defined by a call to eval.
• isNative: Returns true if this call is in native V8 code.
• isConstructor: Returns true if this is a constructor call.
• isAsync(): Returns true if this call is asynchronous (i.e. await, Promise.all(), or Promise.any()).
• isPromiseAll(): Returns true if this is an asynchronous call to Promise.all().
• getPromiseIndex(): Returns the index of the promise element that was followed in Promise.all() or Promise.any() for async stack traces, or null if the CallSite is not an asynchronous Promise.all() or Promise.any() call.