<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>跨浏览器placehoder</title>
<meta name="author" content="ifrans.cn" />
<meta name="description" content="跨浏览器的placehoder原生js版,让ie也支持placehoder" />
<meta name="keywords" content="跨浏览器,placehoder,ie,原生js,表单" />
<style>
input{ vertical-align:middle; margin-left:10px; line-height:24px; width:200px; padding-left:2px; }
textarea{ vertical-align:middle; margin-left:10px; width:200px; height:50px; font:inherit; padding-left:2px;}
.wrap-statistics{ visibility:hidden;}
</style>
</head>
<body>
<form id="form1">
<h3>在不支持placeholder的浏览器下，通过插入悬浮的span元素方式模拟</h3>
<p><label for="username1">用户名:</label><input type="text" name="username1" id="username1" placeholder="请输入用户名" value="" required></p>
<p><label for="password1">密 码:</label><input type="password" name="password1" id="password1" placeholder="请输入密码" value="" required></p>
<p><label for="address1">地 址:</label><input type="text" name="address1" id="address1" placeholder="请输入地址" value="" required></p>
<p><label for="remarks1">备 注:</label><textarea placeholder="请输入备注" id="remarks1"></textarea></p>
</form>
<form id="form2">
<h3>通过value方式模拟placeholder</h3>
<p><label for="username2">用户名:</label><input type="text" name="username1" id="username2" placeholder="请输入用户名" value="" required></p>
<p><label for="address2">地 址:</label><input type="text" name="address1" id="address2" placeholder="请输入地址" value="" required></p>
<p><label for="remarks2">备 注:</label><textarea placeholder="请输入备注" id="remarks2"></textarea></p>
</form>
<script>
var oForm1 = document.getElementById(‘form1‘);
var oForm1Inputs = oForm1.getElementsByTagName(‘input‘);
for(var i=0;i<oForm1Inputs.length;i++){
placeHolder(oForm1Inputs[i],true);
}
var oForm1Textarea = oForm1.getElementsByTagName(‘textarea‘)[0];
placeHolder(oForm1Textarea,true);
var oForm2 = document.getElementById(‘form2‘);
var oForm2Inputs = oForm2.getElementsByTagName(‘input‘);
for(var i=0;i<oForm2Inputs.length;i++){
placeHolder(oForm2Inputs[i]);
}
var oForm2Textarea = oForm2.getElementsByTagName(‘textarea‘)[0];
placeHolder(oForm2Textarea);
/**
*
@name placeHolder
*
@class 跨浏览器placeHolder,对于不支持原生placeHolder的浏览器，通过value或插入span元素两种方案模拟
*
@param {Object} obj 要应用placeHolder的表单元素对象
*
@param {Boolean} span 是否采用悬浮的span元素方式来模拟placeHolder，默认值false,默认使用value方式模拟
*/
function placeHolder(obj, span) {
if (!obj.getAttribute(‘placeholder‘)) return;
var imitateMode = span===true?true:false;
var supportPlaceholder = ‘placeholder‘ in document.createElement(‘input‘);
if (!supportPlaceholder) {
var defaultValue = obj.getAttribute(‘placeholder‘);
if (!imitateMode) {
obj.onfocus = function () {
(obj.value == defaultValue) && (obj.value = ‘‘);
obj.style.color = ‘‘;
}
obj.onblur = function () {
if (obj.value == defaultValue) {
obj.style.color = ‘‘;
} else if (obj.value == ‘‘) {
obj.value = defaultValue;
obj.style.color = ‘#ACA899‘;
}
}
obj.onblur();
} else {
var placeHolderCont = document.createTextNode(defaultValue);
var oWrapper = document.createElement(‘span‘);
oWrapper.style.cssText = ‘position:absolute; color:#ACA899; display:inline-block; overflow:hidden;‘;
oWrapper.className = ‘wrap-placeholder‘;
oWrapper.style.fontFamily = getStyle(obj, ‘fontFamily‘);
oWrapper.style.fontSize = getStyle(obj, ‘fontSize‘);
oWrapper.style.marginLeft = parseInt(getStyle(obj, ‘marginLeft‘)) ? parseInt(getStyle(obj, ‘marginLeft‘)) + 3 + ‘px‘ : 3 + ‘px‘;
oWrapper.style.marginTop = parseInt(getStyle(obj, ‘marginTop‘)) ? getStyle(obj, ‘marginTop‘): 1 + ‘px‘;
oWrapper.style.paddingLeft = getStyle(obj, ‘paddingLeft‘);
oWrapper.style.width = obj.offsetWidth - parseInt(getStyle(obj, ‘marginLeft‘)) + ‘px‘;
oWrapper.style.height = obj.offsetHeight + ‘px‘;
oWrapper.style.lineHeight = obj.nodeName.toLowerCase()==‘textarea‘? ‘‘:obj.offsetHeight + ‘px‘;
oWrapper.appendChild(placeHolderCont);
obj.parentNode.insertBefore(oWrapper, obj);
oWrapper.onclick = function () {
obj.focus();
}
//绑定input或onpropertychange事件
if (typeof(obj.oninput)==‘object‘) {
obj.addEventListener("input", changeHandler, false);
} else {
obj.onpropertychange = changeHandler;
}
function changeHandler() {
oWrapper.style.display = obj.value != ‘‘ ? ‘none‘ : ‘inline-block‘;
}
/**
*
@name getStyle
* @class 获取样式
* @param {Object} obj 要获取样式的对象
* @param {String} styleName 要获取的样式名
*/
function getStyle(obj, styleName) {
var oStyle = null;
if (obj.currentStyle)
oStyle = obj.currentStyle[styleName];
else if (window.getComputedStyle)
oStyle = window.getComputedStyle(obj, null)[styleName];
return oStyle;
}
}
}
}
</script>
</body>
</html>