how to take out the day name from the input date without using moment js in react-CodePudding

My code so far checks the date weather its valid or not but i don't know how to get the name of the day for the date i have input in the input field. For example : if i put 12/01/1994 it should print wednesday

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>
                    );
                  }
                }

CodePudding user response：

This should work:

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

const 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";

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

console.log(day)

CodePudding user response：

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)

CodePudding user response：

I think it is better practice to use toLocaleString when you work with dates in javscript, for example, if you will try to use array where you have week days and get the specific string from that by your date format is bad, because on IOS you will get undefined because "12/01/1994" is not a format supported by ECMA-262 so parsing implementation will be dependent and iOS will treat it as an invalid date.

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'))