Javascript idiosyncrasies

To start this blog nothing better than a Javascript behaviour i noticed while working on a given project.
Let's say you submit a date like '2015-06-31' which is invalid. Javascript will do the smart thing, really people
, and consider that date as '2015-07-01' if you create a Date object out of it.
Searching for a solution i came across the following code:

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function isDate(txtDate)
{
    var currVal = txtDate;
    if(currVal == '')
        return false;

    var rxDatePattern = /^(\d{4})(\/|-)(\d{1,2})(\/|-)(\d{1,2})$/; //Declare Regex
    var dtArray = currVal.match(rxDatePattern); // is format OK?

    if (dtArray == null) 
        return false;

    dtMonth = dtArray[3];
    dtDay= dtArray[5];
    dtYear = dtArray[1];        

    if (dtMonth < 1 || dtMonth > 12) 
        return false;
    else if (dtDay < 1 || dtDay> 31) 
        return false;
    else if ((dtMonth==4 || dtMonth==6 || dtMonth==9 || dtMonth==11) && dtDay ==31) 
        return false;
    else if (dtMonth == 2) 
    {
        var isleap = (dtYear % 4 == 0 && (dtYear % 100 != 0 || dtYear % 400 == 0));
        if (dtDay> 29 || (dtDay ==29 && !isleap)) 
                return false;
    }
    return true;
}

From : http://stackoverflow.com/questions/18758772/how-do-i-validate-a-date-in-this-format-yyyy-mm-dd-using-jquery

It seems pretty complete and it has a special case to workaround the behavior at the start of this post.

As an alternative you could create a new Date object and compare dtMonth and dtDay and dtYear to be the same as before.

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function isDate(txtDate)
{
    var currVal = txtDate;
    if(currVal == '')
        return false;
    
    var rxDatePattern = /^(\d{4})(\/|-)(\d{1,2})(\/|-)(\d{1,2})$/; //Declare Regex
    var dtArray = currVal.match(rxDatePattern); // is format OK?
    
    if (dtArray == null) 
        return false;
    
    dtMonth = dtArray[3];
    dtDay=  dtArray[5];
    dtYear = dtArray[1];
    
  
    var date = new Date(txtDate);

    return (date.getMonth()==(dtMonth-1) && date.getDate()==dtDay && date.getFullYear()==dtYear);
}




 

You can test it here - http://jsfiddle.net/EywSP/2282/ 

The month count being from 0 to 11 also makes perfect sense.

My next post will focus on odoo and how to implement a simple questionnaire framework for your clients.