Q:

How to make an 's string/content its value? 

Here's the code:
HTML:
<input type="text" id="name" name="name" placeholder="Your Name" onblur="namerr()">
<br>
<label id="name_labl">This field is required.</label>

CSS:
#name_labl {
    display: none;
}

JavaScript:
var nameForm = document.getElementById("name").value.length;
function namerr() {
                if (nameForm < 1) {
                  document.getElementById("name_labl").style.display="block";
                  document.getElementById("name").style.borderColor="red";
            } else {
                  document.getElementById("name_labl").style.display="none";
                  document.getElementById("name").style.borderColor="black";
            }

I tried using numerous methods, ranging from using var name_form = document.forms["mailSender"]["name"].value.length; instead of document.getElementById("name").value.length; to if (nameForm==null || nameForm=="") instead of nameForm<1. 
None worked.  
You see, whatever I do, I always get the actual value of the <input />, like so – <input type="text" value="some value" />.  However, instead of value, I'm using placeholder.  
No matter what is the text inside the form, I will always get either "0" or simply nothing in case of value.length or just .value, respectively. 
So I decided to make the contents of the <input type="text" /> its value and then measure the length of it to determine whether the form has been filled or not. 
Any ideas about how to do that? 

A:

The value does not update automatically when it changes after you read it.  You need to read it inside the function to get the newest value. 
function namerr() {
    var nameForm = document.getElementById("name").value.length;
    if (nameForm < 1) {
         document.getElementById("name_labl").style.display="block";
         document.getElementById("name").style.borderColor="red";
    } else {
          document.getElementById("name_labl").style.display="none";
          document.getElementById("name").style.borderColor="black";
    }
}

