safer-promise v0.2.1

safer-promise

Social Media Photo by freestocks.org on Unsplash

A Promise that cannot be observed, with resolve and reject methods able to secure other promises too.

// once imported
import SaferPromise, {resolve, reject} from 'safer-function';

// even nasty operations like this would not interfere
const {then} = Promise.prototype;
Object.defineProperties(Promise.prototype, {
  then: {
    value(fn) {
      return typeof fn === 'function' ?
        then.call(this, result => {
          console.log('BUSTED', result);
          return fn(result);
        }) :
        then.call(this, fn, result => {
          console.log('BUSTED', result);
          return result;
        });
    }
  }
});
Object.freeze(Promise);
Object.freeze(Promise.prototype);

// try it to believe it
resolve(123).then(console.log).then(console.log).catch(console.log);

// or even with native promises, i.e.
resolve(fetch('file')).then(...);

Compatibility

The compatibility bar here is defined by a native Symbol.species entity, meaning that every ES2015 engine should work as expected.

This module is specially handy to secure advanced modern features so that old browsers will never be a target goal.