javascript - 获取日期文本函数返回未定义

Question

不确定下面的函数的逻辑缺陷在哪里，我正在尝试获取字符串中的日期值。

function getDayText(date){
        var weekday = new Array(7);

        weekday[0]=  "Sunday";
        weekday[1] = "Monday";
        weekday[2] = "Tuesday";
        weekday[3] = "Wednesday";
        weekday[4] = "Thursday";
        weekday[5] = "Friday";
        weekday[6] = "Saturday";

        return weekday[date];
}

console.log(getDayText(2016-1-1)) // undefined

Answer 1

问题是您的参数 2016-1-1 不是有效日期。

//no need to create array for each call
var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

var day = function(str) {
  var tmp = new Date(str); //create date
  return days[tmp.getDay()];
};

alert(day('2016-1-1')); //<-- note, its string