JS实现获取今年第几天是周几的方法分析

function getWeek(str){  var nowyearstr =Date.parse(new Date().getFullYear());  var nowstr =nowyearstr+str*86400000;  return new Date(nowstr).getDay();}

<script>function getWeek(str){  var nowyearstr =Date.parse(new Date().getFullYear());  var nowstr =nowyearstr+str*86400000;  return new Date(nowstr).getDay();}document.write(getWeek(100))</script>

function getWeek(str){  var nowyearstr =Date.parse(new Date().getFullYear());  var nowstr =nowyearstr+(str-1)*86400000;  return new Date(nowstr).getDay();}

function as(dy){  return ['日', '一', '二', '三', '四', '五', '六'][new Date(new Date().getFullYear(), 0, dy % 7).getDay()];}