CODEWITHSUNDEEP
javascriptfetch-api
Szczepan Hołyszewski
Szczepan Hołyszewski

Reputation: 3175

How to attach data to fetch() request and get it back with response?

Is it possible with the fetch() API to attach arbitrary client-only data to the request and then access it from the response?

I need to attach a sequence number to each request to a particular endpoint and I need it to be somehow available through the corresponding response (in order to know when to silently drop a response to a "superseded" request), but I neither need nor want to send this seq number to the server and require that the server return it.

Upvotes: 0

Views: 312

Answers (1)

Bergi
Bergi

Reputation: 665286

Just store it in the closure:

var seq = 0;
function makeRequest() {
    var cur = ++seq;
    return fetch(…).then(function(response) {
        if (cur < seq)
            throw new Error("has been superseded");
        else
            return response.json();
    });
}

Upvotes: 1

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