HTML/JavaScript: Simple form validation on submit

Question

I'm trying to validate my form with the easiest way possible, but somehow it is not working and when I click submit it just takes me to the next page without giving the alert message:

HTML:

<form name="ff1" method="post" onsubmit="validateForm();">
    <input type="text" name="email" id="fremail" placeholder="[email protected]" />
    <input type="text" name="title" id="frtitle" placeholder="Title" />
    <input type="text" name="url"   id="frurl"   placeholder="http://yourwebsite.com/" />

    <input type="submit" name="Submit" value="Continue" />
</form>

JavaScript:

<script type="text/JavaScript">

function validateURL(url) {
    var reurl = /^(http[s]?:\/\/){0,1}(www\.){0,1}[a-zA-Z0-9\.\-]+\.[a-zA-Z]{2,5}[\.]{0,1}/;
    return re.test(url);
}

function validateForm()
{
    // Validate URL
    var url = $("#frurl").val();
    if (validateURL(url)) { } else {
        alert("Please enter a valid URL, remember including http://");
    }

    // Validate Title
    var title = $("#frtitle").val();
    if (title=="" || title==null) { } else {
        alert("Please enter only alphanumeric values for your advertisement title");
    }

    // Validate Email
    var email = $("#fremail").val();
    if ((/(.+)@(.+){2,}\.(.+){2,}/.test(email)) || email=="" || email==null) { } else {
        alert("Please enter a valid email");
    }
  return false;
}
</script>

Here is also in jsfiddle http://jsfiddle.net/CrLsR/

Answer 1

You have several errors there.

First, you have to return a value from the function in the HTML markup: <form name="ff1" method="post" onsubmit="return validateForm();">

Second, in the JSFiddle, you place the code inside onLoad which and then the form won't recognize it - and last you have to return true from the function if all validation is a success - I fixed some issues in the update:

https://jsfiddle.net/mj68cq0b/

function validateURL(url) {     var reurl = /^(http[s]?:\/\/){0,1}(www\.){0,1}[a-zA-Z0-9\.\-]+\.[a-zA-Z]{2,5}[\.]{0,1}/;     return reurl.test(url); }  function validateForm() {     // Validate URL     var url = $("#frurl").val();     if (validateURL(url)) { } else {         alert("Please enter a valid URL, remember including http://");         return false;     }      // Validate Title     var title = $("#frtitle").val();     if (title=="" || title==null) {         alert("Please enter only alphanumeric values for your advertisement title");         return false;     }      // Validate Email     var email = $("#fremail").val();     if ((/(.+)@(.+){2,}\.(.+){2,}/.test(email)) || email=="" || email==null) { } else {         alert("Please enter a valid email");         return false;     }   return true; } 

Answer 2

The simplest validation is as follows:

<form name="ff1" method="post">   <input type="email" name="email" id="fremail" placeholder="[email protected]" />   <input type="text" pattern="[a-z0-9. -]+" title="Please enter only alphanumeric characters." name="title" id="frtitle" placeholder="Title" />   <input type="url" name="url" id="frurl" placeholder="http://yourwebsite.com/" />   <input type="submit" name="Submit" value="Continue" /> </form>

It uses HTML5 attributes (like as pattern).

JavaScript: none.

Answer 3

You need to return the validating function. Something like:

onsubmit="return validateForm();"

Then the validating function should return false on errors. If everything is OK return true. Remember that the server has to validate as well.