// ! 逻辑非运算符：对照表
console.log(!true);  // false
console.log(!false); // true

示例代码：体温是否正常 判断体温是否正常。

// 判断体温是否正常
textLabel("tempLabelID", "What is your temperature?");
textInput("tempID", "");
button("buttonID", "Submit");
textLabel("tempMessageID1", "");
textLabel("tempMessageID2", "");
onEvent("buttonID", "click", function(event) {
  setText("tempMessageID1","");
  setText("tempMessageID2","");  
  var temp = getText("tempID");
  if (!(temp >= 98 && temp <= 99.5) ) {
    setText("tempMessageID1", "You may be sick.");
  }
  else {
    setText("tempMessageID1", "Your temperature is fine.");
  }
  if (!(temp >= 98) || !(temp <= 99.5) ) {
    setText("tempMessageID2", "You may be sick.");
  }
  else {
    setText("tempMessageID2", "Your temperature is fine.");
  }
});

示例代码：工作时间 9 点到 5 点 判断当前是否为工作时间

// 判断当前是否为工作时间
function IsWorkingHours() {
    var now = new Date();
    var hours = now.getHours();
    var workHours = false;
    if (hours >= 9 && hours < 17) {
        workHours = true;
    }
    return workHours;
}

if (!IsWorkingHours()) {
    console.log('take a break');
} else {
    console.log('get to work');
}