Extending Error in Javascript with ES6 syntax & Babel

Based on Karel Bílek’s answer, I’d make a small change to the constructor:

class ExtendableError extends Error {
  constructor(message) {
    this.name = this.constructor.name;
    if (typeof Error.captureStackTrace === 'function') {
      Error.captureStackTrace(this, this.constructor);
    } else { 
      this.stack = (new Error(message)).stack; 

// now I can extend

class MyError extends ExtendableError {}

var myerror = new MyError("ll");
console.log(myerror instanceof Error);

This will print MyError in the stack, and not the generic Error.

It will also add the error message to the stack trace – which was missing from Karel’s example.

It will also use captureStackTrace if it’s available.

With Babel 6, you need transform-builtin-extend (npm) for this to work.

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