如何在不使用时刻 js 的情况下从输入日期中取出日期名称

Question

到目前为止，我的代码检查日期是否有效，但我不知道如何获取我在输入字段中输入的日期的日期名称。例如：如果我输入 12/01/1994 它应该打印星期三

function isValidDate(inputDate) {
  if (!/^\d{1,2}\/\d{1,2}\/\d{4}$/.test(inputDate)) return false;
  var parts = inputDate.split('/'); //12 01 1994
  var day = parseInt(parts[0], 10);
  var month = parseInt(parts[1], 10);
  var year = parseInt(parts[2], 10);
  if (year < 1000 || year > 3000 || month == 0 || month > 12) return false;
  var monthLength = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
  if (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0)) monthLength[1] = 29;

  return day > 0 && day <= monthLength[month - 1];
}
class Inputdate extends React.Component {
  state = {
    inputDate: '',
    day: '',
  };

  render() {
    console.log(this.state);
    return (
      <div>
        <input
          name="date"
          type="text"
          value={this.state.value}
          placeholder="dd-mm-yyyy"
          onChange={(e) => {
            if (isValidDate(e.target.value)) {
              this.setState({ inputDate: e.target.value });
            } else {
              this.setState({ inputDate: 'invalid date' });
            }
          }}
        />

        <p>{this.state.inputDate}</p>
      </div>
    );
  }
}

Answer 1

我认为在 javscript 中处理日期时使用toLocaleString 是更好的做法，例如，如果您将尝试在有工作日的地方使用数组并通过日期格式从中获取特定字符串是不好的, 因为在 IOS 上你会得到 undefined 因为 "12/01/1994" 不是 ECMA-262 支持的格式，所以解析实现将取决于 iOS 将其视为无效日期。

const getWeekday = (dateFormat) => {
    // split date in non-digit chaarcters
    let [d, m, y] = dateFormat.split(/\D/);

    //put them in Date method
    const date = new Date(y, m - 1, d)
    //and return weekday in long format
    const weekday = date.toLocaleString("default", { weekday: "long" })
    
    return weekday
}

console.log(getWeekday('12/01/1994'))

Answer 2

const event = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));
const options = { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' };

var date = event.toLocaleDateString(undefined, options)


var day =  date.split(',')[0] // This will show you the day name.
console.log(day)

Answer 3

这应该可行：

let d = new Date("12/01/1994")

const weekday = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]

let day = weekday[d.getDay()];

console.log(day)