js 计算现在的时间是今年的第几周
function isDate(value) {
return value instanceof Date || Object.prototype.toString.call(value) === '[object Date]';
}
function toDate(value) {
if (isDate(value)) {
return new Date(value.getTime());
}
if (value == null) {
return new Date(NaN);
}
return new Date(value);
}
function isValidDate(value) {
return isDate(value) && !isNaN(value.getTime());
}
function startOfWeek(value, firstDayOfWeek = 0) {
if (!(firstDayOfWeek >= 0 && firstDayOfWeek <= 6)) {
throw new RangeError('weekStartsOn must be between 0 and 6');
}
const date = toDate(value);
const day = date.getDay();
const diff = (day + 7 - firstDayOfWeek) % 7;
date.setDate(date.getDate() - diff);
date.setHours(0, 0, 0, 0);
return date;
}
function startOfWeekYear(
value,
{ firstDayOfWeek = 0, firstWeekContainsDate = 1 } = {}
) {
if (!(firstWeekContainsDate >= 1 && firstWeekContainsDate <= 7)) {
throw new RangeError('firstWeekContainsDate must be between 1 and 7');
}
const date = toDate(value);
const year = date.getFullYear();
let firstDateOfFirstWeek = new Date(0);
for (let i = year + 1; i >= year - 1; i--) {
firstDateOfFirstWeek.setFullYear(i, 0, firstWeekContainsDate);
firstDateOfFirstWeek.setHours(0, 0, 0, 0);
firstDateOfFirstWeek = startOfWeek(firstDateOfFirstWeek, firstDayOfWeek);
if (date.getTime() >= firstDateOfFirstWeek.getTime()) {
break;
}
}
return firstDateOfFirstWeek;
}
function getWeek(value, { firstDayOfWeek = 0, firstWeekContainsDate = 1 } = {}) {
const date = toDate(value);
const firstDateOfThisWeek = startOfWeek(date, firstDayOfWeek);
const firstDateOfFirstWeek = startOfWeekYear(date, { firstDayOfWeek, firstWeekContainsDate });
const diff = firstDateOfThisWeek.getTime() - firstDateOfFirstWeek.getTime();
return Math.round(diff / (7 * 24 * 3600 * 1000)) + 1;
}
1.把以上的代码复制写成一个js文件。
2.导入这个js文件。
3.使用：
var week0 = getWeek(“传入格式化后的时间，列如：2023-04-26”);