Compare two dates in Javascript from an HTML form

Question

I just started learning php and from time to time I need some JS functions. Today is one of those day. I have an HTML form where I ask for the age of my users and I'd like to check if they put a grater or equal date compared to the today date. This is the HTML code:

var borndate = document.getElementById("borndate");
var date = new Date()
	 
function comparedate(){
	if (borndate >= date.getFullYear()){
			alert("Looks like you are to young!");
                        return false;
	} else {
		return true;
	}
 }

<div class="form">
    	<form class="login-form" method="POST" action="main.php">
    		<input type="date" id="borndate" name="borndate" required="required"/>
                <input type="submit" value="submit" onclick="comparedate()"/>
    	</form>
    </div>

Smollet777 · Accepted Answer · 2018-11-09 07:27:37Z

2

Try it:

// You were wrong comparing only the year with the full date
var todaysYear = new Date().getFullYear();

var borndate = document.getElementById("borndate");
var form = document.querySelector("form");
// Working with forms we want to catch submit (not click) events
form.addEventListener('submit', comparedate)

function comparedate(evt) {
  // preventing default behavior (form submit in this case)
  evt.preventDefault();

  // here we translate 'string' value back to 'date' & extract year
  var yearOfBirth = new Date(borndate.value).getFullYear()
  // an alternative would be to simply parse the year off the string itself

  if (yearOfBirth >= todaysYear) {
    alert("Looks like you are to young!");
  } else {
    // submitting form programmatically
    form.submit()
  }
}

<div class="form">
  <form class="login-form" method="POST" action="main.php">
    <input type="date" id="borndate" name="borndate" required="required" />
    <input type="submit" class="button" name="button" value="submit" />
  </form>
</div>

edited Nov 9, 2018 at 7:27

answered Nov 7, 2018 at 9:05

Smollet777

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7 Comments

TheNoobUser Over a year ago

I actually have a submit button in my form. I want to start this script when someone submit it, so I have: <input type="submit" class="button" name="button" value="submit" onclick="comparedate()"/> and in the function, after the alert i have a return false; to stop the user to go to main.php if the date is the same or grater than the current date. However it's still letting me go to the next page

TheNoobUser Over a year ago

Still letting me go to main.php when I click on submit

Smollet777 Over a year ago

@TheNoobUser and now?

TheNoobUser Over a year ago

on snippet it's working but on my code is still letting me go to main.php, i really have no clue

TheNoobUser Over a year ago

Sorry I forgot to tag you, i just marked your answer as correct, it was a typo on my side. Thank!

|

Mamun · Accepted Answer · 2018-11-07 09:10:14Z

2

Since the variable date is the year, I assume you are trying to compare only the year.

Your code is comparing the element itself with the year. You have to do the comparison with the value of the element.

Change

if (borndate >= date)

To

if (new Date(borndate.value).getFullYear() >= date)

edited Nov 7, 2018 at 9:10

answered Nov 7, 2018 at 8:53

Mamun

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7 Comments

OliverRadini Over a year ago

Does this work? I've not had much success with this. Could you post some code to illustrate how this would be implemented?

OliverRadini Over a year ago

Ah, I see, that makes sense; the new code seems like it would work, as you're now taking a date from the value

TheNoobUser Over a year ago

For me is not working, it let me load into main.php even if i set the borndate to tomorrow

Mamun Over a year ago

@TheNoobUser, do you want to compare the full date??

TheNoobUser Over a year ago

Just the year it's fine. Since is 2018 and I select the date of tomorrow and i have a >= it should not let me do it

|

OliverRadini · Accepted Answer · 2018-11-07 08:58:59Z

I tend to find that libraries make working with dates much easier, and whilst it might be excessive to use one here for something relatively small, you may be interested to see how such an option would work:

var test = dateFns;


function comparedate(){
    var borndate = dateFns.parse(document.getElementById("borndate").value);
    var date = dateFns.parse(new Date());
    
    console.dir(date)
    console.dir(borndate)
    
    if (dateFns.isAfter(borndate, date)) {
        alert("Looks like you are to young!");
    } else {
        return true;
    }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/date-fns/1.29.0/date_fns.min.js"></script>
<div class="form">
    <form class="login-form" method="POST" action="main.php">
        <input type="date" id="borndate" name="borndate" required="required"/>
    </form>
    <button onclick="comparedate()">Compare</button>
</div>

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