{{ date | youbi }}
{{ date | youbi('曜') }}
<div id="app"> <p><input type="date" v-model="date"></p> <p>{{ date | youbi }}</p> <p>{{ date | youbi('曜') }}</p> </div>
new Vue({ el: '#app', data: { date: '2018年12月4日' }, filters: { youbi(date, suffix) { if (!date) return '【無効な日付】' const [y, m, d] = date.replace(/[年月-]/g, '/').replace('日', '').split('/') const _m = +m - 1 const _d = +d const day = '日月火水木金土'.charAt(new Date(y, _m, _d).getDay()) if (suffix) { return `${date} ${day}${suffix}` } else { return `${date} (${day})` } } } })