placeholder在ie789下无效

<input type="text" class="input" placeholder="用户名/手机号码/邮箱" value=""/>

<script>
var inputs=$("input[class $='input']");

for(var i=0;i<inputs.length;i++)
{
if(inputs[i].value==""||inputs[i].value==null)
{
placeHolder(inputs[i],true);
}

}
/**
* @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>