[NodeJS] Get the current function name or any other function while using strict mode

functionName.js

'use strict';

const findFirstOccurrence = (string, searchElements, fromIndex = 0) => {
  let min = string.length;
  for (let i = 0; i < searchElements.length; i += 1) {
    const occ = string.indexOf(searchElements[i], fromIndex);
    if (occ !== -1 && occ < min) {
      min = occ;
    }
  }
  return (min === string.length) ? -1 : min;
}

const functionName = (func = null) => {
  if (func) {
    if (func.name) {
      return func.name;
    }
    const result = /^function\s+([\w\$]+)\s*\(/.exec(func.toString());
    return result ? result[1] : '';
  }
  const obj = {};
  Error.captureStackTrace(obj, functionName);
  const {stack} = obj;
  const firstCharacter = stack.indexOf('at ') + 3;
  const lastCharacter = findFirstOccurrence(stack, [' ', ':', '\n'], firstCharacter);
  return stack.slice(firstCharacter, lastCharacter);
}

module.exports = functionName;

doesn't work in Safari

doesn't work in Safari

Does something work in Safari?

If it is not working in Safari check also in chrome from an Iphone. There are some chances is not even working there. Those s*****s are not happy enough complexing their stuff, they have to limit other's software

Chrome on iOS is still webkit (aka safari). It's just a different UI.

stacktracey seems to work cross browser pretty well

Great job. This is exactly what I was looking for without instantiating a new Error (although it still parses a call stack). Confirmed working in Node v16.13.0. It also may not be clear until you're using it that just calling the function without passing a function will get the current function's name.