您能帮我在我的JavaScript文件中找到未定义的错误吗？

Question

when I console.log it it gives undefined but i checked 10 times bud cant find the erorr!

 let getBody = document.body; let newElement = document.createElement("h1"); let date = new Date(); let currentHour = date.getHours(); let createTxtMsg; if (currentHour >= 4 && currentHour < 10) { createTxtMsg = "Good Morning!"; } else if (currentHour >= 10 && currentHour < 12) { createTxtMsg = "Good Day!"; } else if (currentHour >= 12 && currentHour < 18) { createTxtMsg = "Good Afternoon"; } else if (currentHour >= 18 && currentHour < 22) { createTxtMsg = "Good evening"; } else if (currentHour >= 22 && currentHour < 4) { createTxtMsg = "Good night"; } console.log(createTxtMsg) let createEleTxt = document.createTextNode(createTxtMsg); newElement.appendChild(createEleTxt); getBody.appendChild(newElement); 

Answer 1

your if..else if chain does not check for all conditions, as there is always the possiblity of the currentHour to be less than 4 or (instead of and) more than 22.

To simply account for that condition, simply just add an else statement, or add additional else if statements to handle the additional conditions

.
.
else if (currentHour< 4) {
  createTxtMsg = 'helloo';
}
.
.

Answer 2

There's logical error like comment said.

And I recommend you this approach. This is more readable and easy to understand.

    if (22 <= currentHour) {
      createTxtMsg = "Good night";
    } else if (18 <= currentHour) {
      createTxtMsg = "Good evening";
    } else if (12 <= currentHour) {
      createTxtMsg = "Good Afternoon";
    } else if (10 <= currentHour) {
      createTxtMsg = "Good Day!";
    } else if (4 <= currentHour) {
      createTxtMsg = "Good Morning!";
    } else {
      createTxtMsg = "Good night";
    }

Compelete snippet:

 let getBody = document.body; let newElement = document.createElement("h1"); let date = new Date(); let currentHour = date.getHours(); let createTxtMsg; if (22 <= currentHour) { createTxtMsg = "Good night"; } else if (18 <= currentHour) { createTxtMsg = "Good evening"; } else if (12 <= currentHour) { createTxtMsg = "Good Afternoon"; } else if (10 <= currentHour) { createTxtMsg = "Good Day!"; } else if (4 <= currentHour) { createTxtMsg = "Good Morning!"; } else { createTxtMsg = "Good night"; } console.log(createTxtMsg) let createEleTxt = document.createTextNode(createTxtMsg); newElement.appendChild(createEleTxt); getBody.appendChild(newElement);