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Re: Pause for series of fetch calls

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On 21/05/2021 9:06 am, Andrew Poulos wrote:
> On 20/05/2021 10:08 pm, Jon Ribbens wrote:
>> On 2021-05-20, Andrew Poulos <ap_prog@hotmail.com> wrote:
>>> I need to:
>>>
>>> - make a series of fetch calls
>>> - when they all have resolved do some other normal (non-fetch) calls
>>> - make a another series of fetch calls
>>> - when they all have resolved continue
>>>
>>> I've only used async/await in a very basic way and I've been unable to
>>> work out how make everything wait for the fetch calls to resolve before
>>> making other calls.
>>
>> Do you really mean a *series* of fetch calls? i.e. that each one can
>> only begin once the previous one has completed? Or do you mean you
>> have a set of fetch calls that you want to run in parallel?
>>
>> If it's the former then:
>>
>>    const urls = [ "https://example.com/", "https://example.org/" ... ]
>>    const results = []
>>    for (const url of urls) results.push(await fetch(url))
>>
>> If it's the latter then it depends on what you want to happen if any
>> of the fetches fail. If you want to give up as soon as any of them
>> fail, do:
>>
>>    const results = await Promise.all(urls.map(url => fetch(url)))
>>
>> If you want to always wait for them all to complete, then you could do:
>>
>>    const results = await Promise.all(
>>      urls.map(url => fetch(url).catch(err => err)))
>>
>> and then results will each be a fetch result or an error.
> 
> Sorry but I just don't get it :-(
> 
> I tried this
> 
> const urls = ['upload/test.php','...];
> 
> const results = async () => {
>    await Promise.all(
>      urls.map(url => fetch(url)
>                      .then(response => response.json())
>                      .then(data => {
>                        console.log('Success: ', data);
>                      })
>                      .catch(err => err)));
> };
> 
> results();
> 
> console.log('done');

Doh, it works if I write it correctly

const results = async () => {
   await Promise.all(
     urls.map(url => fetch(url)
                     .then(response => response.json())
                     .then(data => {
                       console.log('Success: ', data);
                     })
                     .catch(err => err)));

   console.log('done');
};

results();

Andrew Poulos

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Thread

Pause for series of fetch calls Andrew Poulos <ap_prog@hotmail.com> - 2021-05-20 19:02 +1000
  Re: Pause for series of fetch calls Julio Di Egidio <julio@diegidio.name> - 2021-05-20 02:24 -0700
    Re: Pause for series of fetch calls Julio Di Egidio <julio@diegidio.name> - 2021-05-20 02:41 -0700
  Re: Pause for series of fetch calls Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-05-20 12:08 +0000
    Re: Pause for series of fetch calls Julio Di Egidio <julio@diegidio.name> - 2021-05-20 05:34 -0700
    Re: Pause for series of fetch calls Andrew Poulos <ap_prog@hotmail.com> - 2021-05-21 09:06 +1000
      Re: Pause for series of fetch calls Andrew Poulos <ap_prog@hotmail.com> - 2021-05-21 09:52 +1000
        Re: Pause for series of fetch calls Jonas Thörnvall <jonas.thornvall@gmail.com> - 2021-05-20 23:34 -0700

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