Getting the object variable name in JavaScript

Question

I am creating a JavaScript code and I had a situation where I want to read the object name (string) in the object method. The sample code of what I am trying to achieve is s

Answer 1

This is definitely possible but is a bit ugly for obvious reasons. I think this can have some application in debugging. The solution makes use of the ability to get the line number for a code using Error object and then reading the source file to get the identifier.

let fs = require('fs');
class Foo {
    constructor(bar, lineAndFile) {
        this.bar = bar;
        this.lineAndFile = lineAndFile;
    }
    toString() {
        return `${this.bar} ${this.lineAndFile}`
    }
}
let foo = new Foo(5, getLineAndFile());

console.log(foo.toString()); // 5 /Users/XXX/XXX/temp.js:11:22
readIdentifierFromFile(foo.lineAndFile); // let foo

function getErrorObject(){
    try { throw Error('') } catch(err) { return err; }
}

function getLineAndFile() {
    let err = getErrorObject();
    let callerLine = err.stack.split("\n")[4];
    let index = callerLine.indexOf("(");
    return callerLine.slice(index+1, callerLine.length-1);
}

function readIdentifierFromFile(lineAndFile) {
    let file = lineAndFile.split(':')[0];
    let line = lineAndFile.split(':')[1];
    fs.readFile(file, 'utf-8', (err, data) => { 
        if (err) throw err; 
        console.log(data.split('\n')[parseInt(line)-1].split('=')[0].trim());
    }) 
}