Node AR Drone Warn on low Battery Status

ar-drone-lowbat.js

/**
 * Warn on console and turn all LEDs red if battery is not charged enough to take off
 * usage:
 * ```client.on('navdata', warnOnLowBat);```
 */
var warnOnLowBat = function (nav){
    if (nav.droneState.lowBattery === 1) {
        this.animateLeds('red', 1, 1);
        console.warn('New battery please!');
    }
}