This example shows the use of Squirrel’s getroottable() function to test for the presence of the imp API nv table object at start-up.

getroottable.device.nut

function startup() {
    // Check if nv table exists and if the key 'count' is in the nv table
    if (!("nv" in getroottable() && "count" in nv)) {
        // Create the nv table as a global variable with the key 'count'
        nv <- { "count" : 0 };
        
        // Add a second nv-persisted key, 'previous'
        nv.previous <- "";
    }

    // Increment the value of 'count' and log the result
    nv.count++;
    local s = format("Pass %i", nv.count);
    server.log("Current message: " + s);
    if (nv.previous.len() > 0) server.log("Last message: " + nv.previous);
    nv.previous = s;

    // Go to deep sleep for ten seconds
    imp.onidle(function(){
        imp.deepsleepfor(10.0);
    });
}

// When the code starts, call the startup() function
startup();