JavaScript僅顯示最后結果

Question

我試圖打印1月1 ^日星期日到來的年份。 問題是它只顯示最后的結果。

 function sun() { var sunday = new Date(); var year; for (year = "2014"; year <= 2050; year++) { var date = new Date(year, 0, 1); if (date.getDay() == 0) document.getElementById('demo').innerHTML = "First Jan being sunday on year =" + year + "<br>"; } } 

 <input type="submit" id="submit" onclick="sun()"> 

Answer 1

將+添加到表達式中

 document.getElementById('demo').innerHTML += "First Jan being sunday on year ="+year+"<br>"; 

Answer 2

function sun(){

var sunday = new Date();
var year;

for (year = "2014"; year <= 2050; year++){
    var date = new Date(year,0,1);
    if (date.getDay()==0)
    //you are overwriting the content of 'demo' each time, changed to "+=" so it adds new HTML each time
    document.getElementById('demo').innerHTML += "First Jan being sunday on year ="+year+"<br>"; 
}

}

Answer 3

在循環的每次迭代中都會替換這些值。

連接結果會有所幫助。

在表達式中使用operator +：

document.getElementById('demo').innerHTML += "First Jan being sunday on year ="+year+"<br>"; 

Answer 4

你應該把“1月1日將在星期日：”靜態的“#demo”里div ，然后使用串連多年+=代替= ， 如 ：

 function sun() { for (let year = 2014; year <= 2050; year++) { if ((new Date(year, 0, 1)).getDay() == 0) { document.getElementById('demo').innerHTML += " " + year; } } } 

 <input type="submit" id="submit" onclick="sun()"> <div id="demo">January 1st will be on Sunday in:</div>