fetch-timeout.js

const FETCH_TIMEOUT = 5000;
let didTimeOut = false;

new Promise(function(resolve, reject) {
    const timeout = setTimeout(function() {
        didTimeOut = true;
        reject(new Error('Request timed out'));
    }, FETCH_TIMEOUT);
    
    fetch('https://davidwalsh.name/?xx1')
    .then(function(response) {
        // Clear the timeout as cleanup
        clearTimeout(timeout);
        if(!didTimeOut) {
            console.log('fetch good! ', response);
            resolve(response);
        }
    })
    .catch(function(err) {
        console.log('fetch failed! ', err);
        
        // Rejection already happened with setTimeout
        if(didTimeOut) return;
        // Reject with error
        reject(err);
    });
})
.then(function() {
    // Request success and no timeout
    console.log('good promise, no timeout! ');
})
.catch(function(err) {
    // Error: response error, request timeout or runtime error
    console.log('promise error! ', err);
});