gistfile1.js

/** 
 * Add this script to the end of your document that use <input autofocus type="text" /> 
 * or <input type="text" placeholder="username" /> and it'll plug support for browser
 * without these attributes
 * Minified version at the bottom
 */
// By remy, from http://gist.github.com/330318
(function () {

function each(list, fn) {
  var l = list.length;
  for (var i = 0; i < l; i++) {
    if (fn.call(list[i], list[i], i, list) === false) {
      break;
    }
  }
}

var addEvent = (function () {
  if (document.addEventListener) {
    return function (el, type, fn) {
      if (el && el.nodeName || el === window) {
        el.addEventListener(type, fn, false);
      } else if (el && el.length) {
        for (var i = 0; i < el.length; i++) {
          addEvent(el[i], type, fn);
        }
      }
    };
  } else {
    return function (el, type, fn) {
      if (el && el.nodeName || el === window) {
        el.attachEvent('on' + type, function () { return fn.call(el, window.event); });
      } else if (el && el.length) {
        for (var i = 0; i < el.length; i++) {
          addEvent(el[i], type, fn);
        }
      }
    };
  }
})();

var i = document.createElement('input'), 
    inputs = [].slice.call(document.getElementsByTagName('input'), 0);

inputs = inputs.concat([].slice.call(document.getElementsByTagName('textarea'), 0));

if (!('placeholder' in i)) {
  // placeholder fix
  each(inputs, function (el) {
    // note - we're using el instead of this across the board because it compresses better
    var lastValue = el.value, placeholder = el.getAttribute('placeholder');
    
    var focus = function () {
      if (el.value == placeholder) {
        el.value = '';
        el.style.color = '';
      }
    };

    var blur = function () {
      if (placeholder && el.value == '') {
        el.value = placeholder;
        el.style.color = '#A29797';
      }
    };
    
    addEvent(el, 'focus', focus);
    addEvent(el, 'blur', blur);
    
    // remove the placeholder if the page is reload or the form is submitted
    addEvent(el.form, 'submit', function () { focus.call(el); });
    addEvent(window, 'unload', function () { focus.call(el); });
    
    // set the default state
    if (el.value == '') {
      blur.call(el);
    }
  });
}

if (!('autofocus' in i)) {
  // auto focus
  each(inputs, function (el) {
    if (el.getAttribute('autofocus') != null) {
      el.focus();
      return false; // "there can only be one"
    }
  });
}
  
})();