解决IE8、IE9 placeholder 不兼容的问题

html:

<input type="text" maxlength="30" name="username" class="input-txt" placeholder="请输入您的姓名">

js:

  $("[placeholder]")
    .focus(function() {
      var input = $(this);
      if (input.val() == input.attr("placeholder")) {
        input.val("");
        input.removeClass("placeholder");
      }
    })
    .blur(function() {
      var input = $(this);
      if (input.val() == "" || input.val() == input.attr("placeholder")) {
        input.addClass("placeholder");
        input.val(input.attr("placeholder"));
      }
    })
    .blur()
    .parents("form")
    .submit(function() {
      $(this).find("[placeholder]").each(function() {
        var input = $(this);
        if (input.val() == input.attr("placeholder")) {
          input.val("");
        }
      });
    });

css:

input::-webkit-input-placeholder, textarea::-webkit-input-placeholder { 
    color:    #666;
}
input:-moz-placeholder, textarea:-moz-placeholder { 
    color:    #666;
}
input::-moz-placeholder, textarea::-moz-placeholder { 
    color:    #666;
}
input:-ms-input-placeholder, textarea:-ms-input-placeholder { 
    color:    #666;
}