JavaScript代碼不打印今天的日期，但昨天

Question

我有以下代碼：

var value_ = "2017-06-01"; 

value_ = value_.split(".")[0]; 
value_ = value_.replace(" ","T"); 
var dateObject = new Date(value_); 

formattedDate = (dateObject.getMonth() + 1) + "/" + dateObject.getDate() + "/" + dateObject.getFullYear(); 

alert(formattedDate); 

JSFiddle here:

它打印日期寫錯了，爲什麼呢？

Answer 1

如果你想打印今天的日期，這裏是一個辦法：

var dateObject = new Date(); 

formattedDate = (dateObject.getMonth() + 1) + "/" + dateObject.getDate() + "/" + dateObject.getFullYear(); 

alert(formattedDate); 

Answer 2

如果你必須從一個字符串構造一個Date對象，使用Date.parse();在正確的格式的字符串。不要將字符串直接傳遞給Date()構造函數。

// Use correct string format (this assumes that you have no control over the 
 
// string's format). 
 
var dateString = "2017-06-01"; 
 

 
// That format could be invalid, so we need to correct it. 
 
var dateObject = new Date(dateString.replace("-", " ")); 
 

 
console.log("The date is: " + dateObject); 
 

 
formattedDate = (dateObject.getMonth() + 1) + "/" + dateObject.getDate() + "/" + dateObject.getFullYear(); 
 

 
console.log(formattedDate);

但是，如果你想當前的日期，只是實例化一個新的日期不帶參數：

var today = new Date();