navigator.sendBeacon aproach

sendBeacon.js

/**
 * SendBeacon - beaultifull unopinated aproach
 * @param {String} uri - target URL (absolute or relative)
 * @param {Object} data - JavaScript {Object} to serialize with `JSON.stringify()`
 * @param {String} auth - optional server authentication key/nonce to request (merge to data)
 */
function Beacon(uri, data, auth = false) {
    // is Chrome?
    let isChrome = !!window.chrome && !window.opera || !navigator.userAgent.indexOf(' OPR/') >= 0
    try {
        if ( auth ) {
            data.auth = auth
        }
        let serializedData = JSON.stringify(data),
            rawData = false
        /**
         * Chrome bug not support Blob.type === 'application/json'
         * @see https://bugs.chromium.org/p/chromium/issues/detail?id=490015
         */
        if ( isChrome ) {
            rawData = new Blob([serializedData], {
                type: 'application/x-www-form-urlencoded'
            })
        } else {
            rawData = new Blob([serializedData], {
                type: 'application/json'
            })
        }
        // send
        if ( rawData ) {
            navigator.sendBeacon(uri, rawData)
        }
    } catch(ex) {}
}