Question

我如何在外部Java脚本文件中写一个像这样的日期2019年2月13日星期三？

Answer 1

function formatDate(date) {
  var monthNames = [
    "January", "February", "March",
    "April", "May", "June", "July",
    "August", "September", "October",
    "November", "December"
  ];
  
  var dayofweek=[
     "Sunday","Monday","Tuesday","Wednesday",
     "Thursday","Friday","Saturday"];

  var day = date.getDate();  
  var monthIndex = date.getMonth();
  var year = date.getFullYear();  
  var dowIdx = date.getDay();
 
  return( dayofweek[dowIdx] + ', ' + monthNames[monthIndex] + ' ' +day + " " + year);
}

console.log(formatDate(new Date()));

Answer 2

此解决方案使用Intl.DateTimeFormat()，因此我们可以利用FormatToParts()函数，然后应用自定义map()，最后是reduce()，以获得所需的输出。

在map()函数中，我们将day值后的literal的值替换为逗号（默认为逗号）。

在MDN上的引用：

DateTimeFormat
Date Format Options
Locales Argument-我们使用undefined来使用用户的默认值
FormatToParts

const d = new Date();

const formatOptions = {
    weekday: 'long',
    month: 'long',
    day: 'numeric',
    year: 'numeric',
    hour12: true
};

// Using Intl.DateTimeFormat so we have access to
//     formatToParts function which produces
//     an Array of objects containing the formatted date in parts
const dateFormat = new Intl.DateTimeFormat(undefined, formatOptions);

// Keep track of 'literal' key counts (`literal` is the separator)
let separatorIndex = 0;

// Where the magic happens using map() and reduce()
const dateString = dateFormat.formatToParts(d).map(({type, value}) => {
  switch (type) {
    case 'literal' :
      separatorIndex++;
      
      switch (separatorIndex) {
        case 3 : // Day separator
          return ' ';
        default: return value;
      }
      break;
  	default: return value;
  }
})
.reduce((string, part) => {
  return string.concat(part)
});

// Not part of answer; only for output result
document.write(dateString);

如何在外部JS中编写今天的特定格式

2 个答案: