// var minimalUserResponseInMiliseconds = 100;
    //   var before = new Date().getTime();
    //   debugger;
    //   var after = new Date().getTime();
    //   if (after - before > minimalUserResponseInMiliseconds) { // user had to resume the script manually via opened dev tools 
    //     document.write('<h1>你是机器人</h1>');
    //   }



 console.log(Object.defineProperties(new Error, {
        message: {get() {alert('Chrome/Firefox')}},
        toString: {value() {(new Error).stack.includes('toString@')&&alert('Safari')}}
      }));


https://blog.aepkill.com/demos/devtools-detector/