text: // Check time every 30 seconds (leave this tab running in the background)
  // If min = 1000 * 1, for example, a new window would open every 1000 * 1 ms
  //  aka every one second
  var min = 1000 * 30;
  setInterval(hi, min);
  
  // Defines the function
  function hi() {
    // The end times of class - 5 minutes
    let endTimes = [
      '9:27', '10:16', '11:05', '11:50', '2:02', '2:51', '3:40'
    ];
  
    let d = new Date();
    let hours = d.getHours();
    let min = d.getMinutes();
  
    // Current time as a string
    let ourTime = hours + ':' + min;
    let len = endTimes.length;
  
    // Check current time with saved times 
    for (let index = 0; index < len; index++) {
      if ( endTimes[index] === ourTime ) {
        window.open('warning.html');
      }
    }
  }
  