Rethrowing error in promise catch

Question

I found the following code in a tutorial:

promise.then(function(result){
    //some code
}).catch(function(error) {
    throw(error);
});

I\'m

Answer 1

In the promise chain, it is better to use .catch

ex in function f2: .then(...).catch(e => reject(e));

• test1 - with try catch
• test2 - without try or .catch
• test3 - with .catch

function f1() {
    return new Promise((resolve, reject) => {
        throw new Error('test');
    });
}

function f2() {
    return new Promise((resolve, reject) => {
        f1().then(value => {
            console.log('f1 ok ???');
        }).catch(e => reject(e));
    });
}

function test1() {
    console.log('test1 - with try catch - look in F12');
    try {
      f2().then(() => { // Uncaught (in promise) Error: test
        console.log('???'); });
    } catch (e) {
      console.log('this error dont catched');
    }
}

function test2() {
    console.log('test2 - without try or .catch - look in F12');
    f2(); // Uncaught (in promise) Error: test
}

function test3() {
  console.log('test3 - with .catch');
  f2().then(value => {
    console.log('??');
  }).catch(e => {
    console.log(' now its ok, error ', e);
  })
}

setTimeout(() => { test1(); 
  setTimeout(() => { test2(); 
    setTimeout(() => { test3(); 
    }, 100);
  }, 100);
}, 100);