Question

—updated fiddle still not functioning http://www.jsfiddle.net/atZPn/5 Trying to get the text in the input box to stay dark only if data has been entered.

http://jsfiddle.net/atZPn/5/

code:

   $(".searchbox").blur(function() {
    var searchbox = this,
        searchbox_val = $.trim( this.value );
    if (searchbox_val.length > 0) {
        return true;
    } else {
        $(searchbox).addClass("blur");
        return false;
    }
});

Answer 1

getElementByClassName should getElementsByClassName and searchbox_val should searchbox_val[0].

/* Search Box Leave */
$(".searchbox").blur(function() {
    var searchbox_val = document.getElementsByClassName("searchbox");
    if (searchbox_val[0].value.length > 0) {
        return true;
    }
    else {
        $(this).addClass("blur");
        return false;
    }
});

Yon can try also like following:

$(".searchbox").blur(function() {
    var searchbox = $(this),
        searchbox_val = $.trim( searchbox.val() );
    if (searchbox_val.length > 0) {
        return true;
    } else {
        searchbox.addClass("blur");
        return false;
    }
});

[Updated]

HTML

<input class="searchbox" type="text" placeholder="Just some text" />

jQuery

$(".searchbox").blur(function() {
    var searchbox = this,
        searchbox_val = $.trim( this.value );
    if (searchbox_val.length > 0) {
        $(searchbox).addClass("blur");
        return true;
    } else {
        $(searchbox).removeClass("blur");
        return false;
    }
});

DEMO