method babel decorators isn't executed

Question

I'm using the babel 7 decorator plugin and I have a simple class and I want to decorate each method in a simple try catch wrapper.

This is what've done:

const errorHandler = () => {
  return (target, property, descriptor) => {
    try {
      return descriptor
    } catch (e) {
      console.error('error from the decorator', e)
    }
  }
}

In this is a sample of my class:

class Example {
  @errorHandler
  addComponent() {
    throw new Error('Error')
  }
}

But when I'm executing the function it's not going throw the decorator before execution, only pre-evaluating when the class is being initialized.

any ideas?

Answer 1

You are returning descriptor, which is a function object and it gets executed by caller outside your try/catch block. To intercept exception - you should execute descriptor yourself.

The correct code is:

const errorHandler = (target, property, descriptor) => {
  const original = descriptor.value;
  if (typeof original === 'function') {
    descriptor.value = async function(...args) {
      try {
        return await original.apply(this, args);
      } catch (e) {
        console.error('error from the decorator', e)
      }
    }
  }
}

class Example {
  @errorHandler
  addComponent() {
    throw new Error('Error')
  }
}

new Example().addComponent();