Question

我有这个示例代码（需要使用.js库）来格式化日期。之前从未使用过部分功能，所以不太确定如何使用它。怎么叫他们？这是实用程序库代码：

 define(function() {
    'use strict';

     function _formatDate(justNowText, todayFormat, thisWeekFormat, thisYearFormat, veryOldFormat, date) {
       if (!date) { return ""; }

         var formattedMoment = moment(date);
         var now = moment();

       if (now.diff(formattedMoment, "minutes") < 15) {
         return justNowText || "Just now";
       }

       var today = now.startOf('day');
       var dateFormat;

       if (today <= formattedMoment) {
         dateFormat = todayFormat;
       } else if (now.diff(formattedMoment, "days") < 7) {
         dateFormat = thisWeekFormat;
       } else if (formattedMoment.year() >= now.year()) {
         dateFormat = thisYearFormat;
       } else {
         dateFormat = veryOldFormat;
       }

      return formattedMoment.format(dateFormat);

    }

    function asShortTimeStampFilter(gettext) {
     return _.partial(_formatDate,
       gettext("Just now"),
       "h:mm A",
       "ddd",
       "MMM D",
       "M/D/YY"
     );
   }

  function asMediumTimeStampFilter(gettext) {
    return _.partial(_formatDate,
      gettext("Just now"),
      "[" + gettext("Today at") + "] h:mm a",
      "ddd h:mm a",_formatDate
      "MMM D h:mm a",
      "M/D/YYYY h:mm a"
    );
  }

  function asDateTimeFormatFilter(gettext) {
    return function(date, format) {
      if (!date) { return; }

      return moment(date).format(format);
    };
  }

  return {
    asShortTimeStamp: ['gettext', asShortTimeStampFilter],
    asMediumTimeStamp: ['gettext', asMediumTimeStampFilter],
    asDateTimeFormat: ['gettext', asDateTimeFormatFilter]
  };
});

Answer 1

Partial application意味着您只传递第一个参数以获取函数，然后您可以使用最终参数调用（多次）。

在你的情况下，库需要一个文本getter函数（例如用于本地化），并返回你传递日期的实际格式化函数。

function id(x) { return x } // just echo the input
var shortTimeStamp = library.asShortTimeStamp[1](id);

console.log(shortTimeStamp(Date.now()))
console.log(shortTimeStamp(Date.now() - 30000)) // 30s ago
console.log(shortTimeStamp(Date.now() - 720000)) // 2h ago

var mediumGermanTimeStamp = library.asMediumTimeStamp[1](function(t) {
    return {"Just now":"Grad vorhin", "Today at":"Heut um"}[t];
});

console.log(mediumGermanTimeStamp(Date.now()))
console.log(mediumGermanTimeStamp(Date.now() - 30000)) // 30s ago
console.log(mediumGermanTimeStamp(Date.now() - 720000)) // 2h ago

如何调用部分功能

1 个答案: