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Text boxes and password boxes implement gray pre-prompt text

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Release: 2018-04-26 13:46:45
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这次给大家带来文本框和密码框实现灰色预提示文字,文本框和密码框实现灰色预提示文字的注意事项有哪些,下面就是实战案例,一起来看一下。

很久之前写了这个插件,基于jQuery实现的,主要用于IE下实现placeholder效果,可同时支持文本和密码输入框。

placeholder是HTML5新增的一个属性,当input设置了该属性后,该值的内容将作为灰色提示显示在文本框中,当文本框获得焦点时,提示文字消失。

实现代码如下:

(function($) {
     var placeholderfriend = {
    focus: function(s) {
      s = $(s).hide().prev().show().focus();
      var idValue = s.attr("id");
      if (idValue) {
        s.attr("id", idValue.replace("placeholderfriend", ""));
      }
      var clsValue = s.attr("class");
   if (clsValue) {
        s.attr("class", clsValue.replace("placeholderfriend", ""));
      }
    }
  }
    //判断是否支持placeholder
  function isPlaceholer() {
    var input = document.createElement('input');
    return "placeholder" in input;
  }
  //不支持的代码
  if (!isPlaceholer()) {
    $(function() {
      var form = $(this);
      //遍历所有文本框,添加placeholder模拟事件
      var elements = form.find("input[type='text'][placeholder]");
      elements.each(function() {
        var s = $(this);
        var pValue = s.attr("placeholder");
  var sValue = s.val();
          if (pValue) {
          if (sValue == '') {
            s.val(pValue);
          }
        }
      });
      elements.focus(function() {
        var s = $(this);
        var pValue = s.attr("placeholder");
  var sValue = s.val();
        if (sValue && pValue) {
          if (sValue == pValue) {
            s.val('');
          }
        }
      });
            elements.blur(function() {
        var s = $(this);
        var pValue = s.attr("placeholder");
  var sValue = s.val();
        if (!sValue) {
          s.val(pValue);
        }
      });
      //遍历所有密码框,添加placeholder模拟事件
      var elementsPass = form.find("input[type='password'][placeholder]");
      elementsPass.each(function(i) {
        var s = $(this);
        var pValue = s.attr("placeholder");
  var sValue = s.val();
        if (pValue) {
          if (sValue == '') {
                      //DOM不支持type的修改,需要复制密码框属性,生成新的DOM
            var html = this.outerHTML || "";
            html = html.replace(/\s*type=(['"])?password\1/gi, " type=text placeholderfriend")
              .replace(/\s*(?:value|on[a-z]+|name)(=(['"])?\S*\1)?/gi, " ")
              .replace(/\s*placeholderfriend/, " placeholderfriend value='" + pValue
              + "' " + "onfocus='placeholderfriendfocus(this);' ");
            var idValue = s.attr("id");
            if (idValue) {
              s.attr("id", idValue + "placeholderfriend");
            }
            var clsValue = s.attr("class");
   if (clsValue) {
              s.attr("class", clsValue + "placeholderfriend");
            }
            s.hide();
            s.after(html);
          }
        }
      });
            elementsPass.blur(function() {
        var s = $(this);
        var sValue = s.val();
        if (sValue == '') {
          var idValue = s.attr("id");
          if (idValue) {
            s.attr("id", idValue + "placeholderfriend");
          }
          var clsValue = s.attr("class");
    if (clsValue) {
            s.attr("class", clsValue + "placeholderfriend");
          }
          s.hide().next().show();
        }
      });
    });
  }
    window.placeholderfriendfocus = placeholderfriend.focus;
})(jQuery);
<html>
<head>
<script src="jquery.js" type="text/javascript"></script>
<script src="placeholderfriend.js" type="text/javascript"></script>
</head>
<body>
<input placeholder="账号/手机号码" ><br>
<input placeholder="密码" type="password" >
</body>
</html>
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