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Regular Expression for MM/DD/YYYY in Javascript

Asked 2011-06-19T13:51:53.503
10

I've just written this regular expression in javaScript however it doesn't seem to work, here's my function:

function isGoodDate(dt){
    var reGoodDate = new RegExp("/^((0?[1-9]|1[012])[- /.](0?[1-9]|[12][0-9]|3[01])[- /.](19|20)?[0-9]{2})*$/");
    return reGoodDate.test(dt);
}

and this is how I call it in my form validation

if(!isGoodDate(userInput[1].value)){
           alert("date not in correct format of MM/dd/YYYY");
           return false;  
        }

now I want it to return MM/DD/YYYY however if I put a valid date in it raises the alert? Any ideas anyone?

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2

I don't think you need a regular expression for this. Try this:

function isGoodDate(dt){
    var dts  = dt.split('/').reverse()
       ,dateTest = new Date(dts.join('/'));
    return isNaN(dateTest) ? false : true;
}

//explained
    var dts  = dt.split('/').reverse()
//      ^ split input and reverse the result
//        ('01/11/2010' becomes [2010,11,01]
//        this way you can make a 'universal' 
//        datestring out of it
       ,dateTest = new Date(dts.join('/'));
//     ^ try converting to a date from the 
//       array just produced, joined by '/'
    return isNaN(dateTest) ? false : true;
//         ^ if the date is invalid, it returns NaN
//           so, if that's the case, return false
answered 2011-06-19T14:10:54.930

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