Question

HTML：

在输入文本字段中输入一年（例如2004）。如何使用JavaScript自动计算当年哪个星期圣诞节降临？

Answer 1

var year = 2004,    //year
    dateObj = new Date(year, 11, 25);   //Note: 11 means "December"

dateObj.getDay();                                         //6
//Most reliable value.

dateObj.toString().substr(0, 3);                          //"Sat"
//Note: Although the specification does not specify the format of the returned
//      value of .toString, in most browsers, the first term should be the 
//      name of the day of the week. If you prefer a more "reliable" method,
//      use a custom Array with day names.

dateObj.toLocaleString("en", {weekday: "long"})       //"Saturday"
//Available in new browsers.

关于

Date构造函数，请参阅here。

Date.prototype.toString，请参阅here。

.toLocaleDateString，请参阅here。

<强>演示

http://jsfiddle.net/DerekL/dbnj2/ _{^{（jQuery仅用于DOM操作）}}

Answer 2

如果您可以将年份输入分配给变量

var year = 2004 // Year entered into field input

然后，您可以执行以下操作以获取特定假期的星期几：

// Use this array to create day of the week names:
var dayStringArray = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];

// Create date of holiday with year entered.
var xmas = new Date(year, 11, 25); // 11 is for December (i.e. 12 - 1)
// This creates a Date object of Dec 25th, 2004

// Get day of week in 0 - 6 integer, then use array to get day text.
var xmasDayString = dayStringArray[xmas.getDay()];

console.log(xmasDayString); // Outputs "Saturday"

Answer 3

halfnibble非常接近，但不必要地使用字符串解析而不是离散值。

function getChristmasDayName(year) {
  var dayNames = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];
  var d = new Date(year, 11, 25);
  d.setFullYear(year); // required to support years 0 to 99
  return dayNames[d.getDay()];
}

alert(getChristmasDayName(2004)); // Saturday

以上假设英文日名称和公历。对其他语言的支持将需要该语言中的其他日期名称数组。支持其他日历需要更多工作。

如何自动计算给定年份的日期？

3 个答案: