javascript - 为什么 startDate 会随着 currentDate 一起增加？

Question

我不明白为什么在下面的脚本中，startDate 随 currentDate 一起更改，但 name1 保持不变。

getWorkdays('01/03/2017', '05/03/2017', 'Jimmy');
function getWorkdays (startDate, endDate, name1) {

    var startDate = nlapiStringToDate(startDate);
    var endDate = nlapiStringToDate(endDate);
    var name1 = name1;

    nlapiLogExecution('DEBUG', 'Conversion of String to Date', 'startDate is now ' + startDate + ' and endDate ' + endDate + ' and the name is ' + name1);

    var name2 = name1;
    var currentDate = startDate;
    nlapiLogExecution('DEBUG', '', 'The currentDate is'+ currentDate + ' and the startDate is ' + startDate);

        while (currentDate <= endDate) { // Loop through all dates between startDate and endDate

        var weekday = currentDate.getDay(); // Retrieve the weekday (in numeric format with sunday = 0) from the currentDate

        if (weekday == 1 || weekday == 6){ // Perform the following loop only if weekday is a Saturday or Sunday

            nlapiLogExecution('DEBUG', '', 'The weekday number is ' + weekday + ' and the name is ' + name2);

        }

        var name2 = 'Jose';
        currentDate.setDate(currentDate.getDate() + 1); // Go to the next date
        nlapiLogExecution('DEBUG', '', 'name2 is '+ name2 + ' and name1 ' + name1);
        nlapiLogExecution('DEBUG', '', 'The currentDate is'+ currentDate + ' and the startDate is ' + startDate);
    }
}

如何将 startDate 保持在 01/03/2017？

Answer 1

之后

var currentDate = startDate;

currentDate 和 startDate 变量都指向同一个 Date 对象，因此对一个变量所做的更改也会影响另一个变量(两者都“看到”同一个对象)。

之后

var name2 = 'Jose';

name2 变量指向一个新字符串，但这不会改变 name1 指向的内容。要达到与上面相同的效果，您必须对原始字符串进行更改(这在 JavaScript 中是不可能的，因为字符串是不可变的)。

How can the startDate be kept at 01/03/2017?

您需要创建一个新的 Date 对象并使用该对象初始化 currentDate。

var currentDate = nlapiStringToDate(startDate);