vue自定义过滤器的语法

Vue如何自定义过滤器？

在Vue中，过滤器是一种特殊的函数，它可以在模板中使用，以对数据进行处理，过滤器可以用在任何需要格式化数据的地方，例如日期、金额等，本文将介绍如何在Vue中自定义过滤器。

创建过滤器

1、定义过滤器函数

我们需要定义一个过滤器函数，这个函数接收两个参数：原始值和待处理的字符串，在函数内部，我们可以对原始值进行处理，然后返回处理后的字符串。

function formatNumber(value) {
  return value.toFixed(2);
}

2、注册过滤器

接下来，我们需要将这个过滤器注册到Vue实例中，在Vue实例的filters属性中添加一个新的对象，键为过滤器的名称，值为过滤器函数。

new Vue({
  el: 'app',
  data: {
    message: 'Hello Vue!'
  },
  filters: {
    formatNumber: formatNumber
  }
});

3、在模板中使用过滤器

现在我们可以在模板中使用这个过滤器了，过滤器的使用方法是在要过滤的内容前加上管道符(|),后面跟上过滤器的名称和参数。

<div id="app">
  {{ message | formatNumber }}
</div>

注意事项

1、过滤器函数不能直接修改原数据，而是返回一个新的字符串，如果需要修改原数据，可以使用计算属性或者方法。

2、如果需要对多个参数进行过滤，可以在过滤器函数中依次处理这些参数。

function formatCurrency(value, currency) {
  return value + ' ' + currency;
}

相关问题与解答

1、如何实现自定义全局过滤器？

答：在Vue实例的filters属性中添加一个新的对象，键为过滤器的名称，值为过滤器函数即可，这样就可以实现自定义全局过滤器。

Vue.filter('capitalize', function (value) {
  if (!value) return '';
  value = value.toString();
  return value.charAt(0).toUpperCase() + value.slice(1);
});

2、如何实现带参数的自定义过滤器？

答：在过滤器函数中依次处理传入的参数即可。

function formatDate(value, dayFormat) {
  var date = new Date(value);
  var year = date.getFullYear();
  var month = date.getMonth() + 1;
  var day = date.getDate();
  var hour = date.getHours();
  var minute = date.getMinutes();
  var second = date.getSeconds();
  if (dayFormat === 'short') {
    return [year, month, day].join('/');
  } else if (dayFormat === 'long') {
    return [year, month, day].join('-');
  } else if (dayFormat === 'full') {
    return [year, month, day].join('年');
  } else if (dayFormat === 'custom') {
    return [hour, minute, second].join('时分秒');
  } else if (dayFormat === 'time') {
    return [year, month, day].join('-');
  } else if (dayFormat === 'date') {
    return [year, month].join('/');
  } else if (dayFormat === 'month') {
    Array.prototype.splice.apply(month, [1, 0].concat(Array.from(["0" + (month < 10 && month >=0)]))); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('-'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e.g. "Jan") and ensure that months are always two digits long for consistency with other parts of the API (e.g. "01" instead of "1") when using this filter in conjunction with the formatDate method or any other methods that use the standard date/time formats provided by the browser's native Date object.return [year, month].join('/'); // zero pad single digit months in the browser's date string output (e