// JavaScript Document

// alert("overlabel.js loaded");
/* 
provides field labels inside form fields to establish compact form layouts
source: http://www.alistapart.com/articles/makingcompactformsmoreaccessible

uses CSS:

div#username,
div#password {
	position:relative;
	float:left;
	margin-right:3px;
}

input#username-field,
input#password-field {
	width:10em;
}

label.overlabel {
	color:#999;
}
label.overlabel-apply {
	position:absolute;
	top:3px;
	left:5px;
	z-index:1;
	color:#999;
}

and uses HTML:

<div id="username">
	<label for="username-field" class="overlabel">Username</label>
	<input id="username-field" type="text" name="username" title="Username" value="" tabindex="1" />
</div>

<div id="password">
	<label for="password-field" class="overlabel">Password</label>
	<input id="password-field" type="password" name="password" title="Password" value="" tabindex="2" />
</div>

*/

function initOverLabels () {
  if (!document.getElementById) return;  	

  var labels, id, field;

  // Set focus and blur handlers to hide and show 
  // LABELs with 'overlabel' class names.
  labels = document.getElementsByTagName('label');
  for (var i = 0; i < labels.length; i++) {
	
    if (labels[i].className == 'overlabel') {

      // Skip labels that do not have a named association
      // with another field.
      id = labels[i].htmlFor || labels[i].getAttribute('for');
      if (!id || !(field = document.getElementById(id))) {
        continue;
      }

      // Change the applied class to hover the label 
      // over the form field.
      labels[i].className = 'overlabel-apply';

      // Hide any fields having an initial value.
      if (field.value !== '') {
        hideLabel(field.getAttribute('id'), true);
      }

      // Set handlers to show and hide labels.
      field.onfocus = function () {
        hideLabel(this.getAttribute('id'), true);
      };
      field.onblur = function () {
        if (this.value === '') {
          hideLabel(this.getAttribute('id'), false);
        }
      };

      // Handle clicks to LABEL elements (for Safari).
      labels[i].onclick = function () {
        var id, field;
        id = this.getAttribute('for');
        if (id && (field = document.getElementById(id))) {
          field.focus();
        }
      };

    }
  }
};

function hideLabel (field_id, hide) {
  var field_for;
  var labels = document.getElementsByTagName('label');
  for (var i = 0; i < labels.length; i++) {
    field_for = labels[i].htmlFor || labels[i].getAttribute('for');
    if (field_for == field_id) {
      labels[i].style.textIndent = (hide) ? '-1000px' : '0px';
      return true;
    }
  }
}

window.onload = function () {
  setTimeout(initOverLabels, 50);
};