1
2
3
4
5

const p = Promise.reject(new Error('Oops!'));

p.catch(err => {
  err.message; 
});

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3
4
5
6
7
8
9
10
11

const p = Promise.resolve('Na');

return p.
  then(str => str + ' Na').
  then(str => str + ' Na').
  then(str => str + ' Na').
  then(() => { throw new Error('Batman!') }).
  then(() => console.log('Will not print')).
  catch(err => {
    err.message; 
  });

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3
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6
7

const p = Promise.reject(new Error('Oops!'));

return p.
  catch(err => { throw err; }). 
  catch(err => {
    err.message; 
  });

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3
4
5
6
7
8
9
10

const p = Promise.reject(new Error('Oops!'));

const answer = await p.catch(() => 42);
answer; 

return p.
  catch(() => 42).
  then(answer => {
    answer; 
  });

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2
3
4

const p = Promise.reject(new Error('Oops!'));

const err = await p.catch(err => err);
err.message; 

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3

Promise.prototype.catch = function(onRejected) {
  return this.then(null, onRejected);
};

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2
3
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5

const p = Promise.reject(new Error('Oops!'));

return p.then(() => {}, function onRejected(err) {
  err.message; 
});