function getDeviceInfo() {
    let rootURL = "https://connect.garmin.com/modern/activity/";
    let loc = window.location.href;
    if (loc.indexOf(rootURL) != 0) {
        console.log("This script must be run on GC device page (with a URL starting with " + rootURL + ")")
        alert("This script must be run on GC device page (with a URL starting with " + rootURL + ")")
        return;
    }
 
    let activityID = loc.replace(rootURL, "");
    var xhr = new XMLHttpRequest();
    xhr.open('GET', 'https://connect.garmin.com/activity-service/activity/' + activityID);
    xhr.setRequestHeader("NK", "NT")
    xhr.setRequestHeader('di-backend', 'connectapi.garmin.com')

    const token = JSON.parse(localStorage.token).access_token;
	xhr.setRequestHeader('Authorization', 'Bearer ' + token);

    xhr.onload = function () {
        let obj = JSON.parse(xhr.response)
        let deviceID = obj.metadataDTO.deviceMetaDataDTO.deviceId;
        console.log('The device ID for this activity is: ' + deviceID)
        alert('The device ID for this activity is: ' + deviceID)
    };
    xhr.send()
}
getDeviceInfo();