JS Double Fetch condition

Question

I'm working in get a list from a local file. But the folder sometimes can change. So come here to ask you guys if it's correct, because I think there is a better way to do it, idk. Please help me :)

  fetch("./myJson.json")
     .then(res => { 
        if(res.status != 404)
           res.json() 
        else
           fetch("../myJson.json")
              .then(res => res.json())
              .then(data => console.log(data))
              .catch(err => console.error(err));
     })
     .then(data => console.log(data))
     .catch(err => console.error(err));

Thanks!

You will need to `return` the nested promises from the callback — Bergi, Nov 24 '18 at 16:12

score 3 · Accepted Answer · answered Nov 24 '18 at 16:14

3

You will need to return the nested promises from the callback and use the promise chaining feature:

fetch("./myJson.json").then(res => { 
    if (res.ok)
        return res.json() 
    else
       return fetch("../myJson.json").then(res => res.json());
}).then(console.log, console.error);

answered Nov 24 '18 at 16:14

Bergi

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Nice Bergi!! Thanks!! Just a detail... If the first fetch fails, an error 404 shows up in console. Can I tell him that "if the first fetch fails, the second one will solve it. You don't have to show any error in console about this first fetch." – Johnson Nov 24 '18 at 16:39
1

The 404 will always show up in the console, you cannot prevent that from JS. You will need to use [different console settings](https://stackoverflow.com/questions/4500741/suppress-chrome-failed-to-load-resource-messages-in-console). Or actually handle the logic on the server side with a redirect. – Bergi Nov 24 '18 at 16:48

JS Double Fetch condition

1 Answers1