js获得指定控件输入光标的坐标兼容IE,Chrome,火狐等多种主流浏览器

直接上代码

var kingwolfofsky = { 
/** 
* 获取输入光标在页面中的坐标 
* @param {HTMLElement} 输入框元素 
* @return {Object} 返回left和top,bottom 
*/ 
getInputPositon: function (elem) { 
if (document.selection) { //IE Support 
elem.focus(); 
var Sel = document.selection.createRange(); 
return { 
left: Sel.boundingLeft, 
top: Sel.boundingTop, 
bottom: Sel.boundingTop + Sel.boundingHeight 
}; 
} else { 
var that = this; 
var cloneDiv = '{$clone_div}', cloneLeft = '{$cloneLeft}', cloneFocus = '{$cloneFocus}', cloneRight = '{$cloneRight}'; 
var none = '<span style="white-space:pre-wrap;"> </span>'; 
var div = elem[cloneDiv] || document.createElement('div'), focus = elem[cloneFocus] || document.createElement('span'); 
var text = elem[cloneLeft] || document.createElement('span'); 
var offset = that._offset(elem), index = this._getFocus(elem), focusOffset = { left: 0, top: 0 }; 
if (!elem[cloneDiv]) { 
elem[cloneDiv] = div, elem[cloneFocus] = focus; 
elem[cloneLeft] = text; 
div.appendChild(text); 
div.appendChild(focus); 
document.body.appendChild(div); 
focus.innerHTML = '|'; 
focus.style.cssText = 'display:inline-block;width:0px;overflow:hidden;z-index:-100;word-wrap:break-word;word-break:break-all;'; 
div.className = this._cloneStyle(elem); 
div.style.cssText = 'visibility:hidden;display:inline-block;position:absolute;z-index:-100;word-wrap:break-word;word-break:break-all;overflow:hidden;'; 
}; 
div.style.left = this._offset(elem).left + "px"; 
div.style.top = this._offset(elem).top + "px"; 
var strTmp = elem.value.substring(0, index).replace(/</g, '<').replace(/>/g, '>').replace(/\n/g, '<br/>').replace(/\s/g, none); 
text.innerHTML = strTmp; 
focus.style.display = 'inline-block'; 
try { focusOffset = this._offset(focus); } catch (e) { }; 
focus.style.display = 'none'; 
return { 
left: focusOffset.left, 
top: focusOffset.top, 
bottom: focusOffset.bottom 
}; 
} 
}, 
// 克隆元素样式并返回类 
_cloneStyle: function (elem, cache) { 
if (!cache && elem['${cloneName}']) return elem['${cloneName}']; 
var className, name, rstyle = /^(number|string)$/; 
var rname = /^(content|outline|outlineWidth)$/; //Opera: content; IE8:outline && outlineWidth 
var cssText = [], sStyle = elem.style; 
for (name in sStyle) { 
if (!rname.test(name)) { 
val = this._getStyle(elem, name); 
if (val !== '' && rstyle.test(typeof val)) { // Firefox 4 
name = name.replace(/([A-Z])/g, "-$1").toLowerCase(); 
cssText.push(name); 
cssText.push(':'); 
cssText.push(val); 
cssText.push(';'); 
}; 
}; 
}; 
cssText = cssText.join(''); 
elem['${cloneName}'] = className = 'clone' + (new Date).getTime(); 
this._addHeadStyle('.' + className + '{' + cssText + '}'); 
return className; 
}, 
// 向页头插入样式 
_addHeadStyle: function (content) { 
var style = this._style[document]; 
if (!style) { 
style = this._style[document] = document.createElement('style'); 
document.getElementsByTagName('head')[0].appendChild(style); 
}; 
style.styleSheet && (style.styleSheet.cssText += content) || style.appendChild(document.createTextNode(content)); 
}, 
_style: {}, 
// 获取最终样式 
_getStyle: 'getComputedStyle' in window ? function (elem, name) { 
return getComputedStyle(elem, null)[name]; 
} : function (elem, name) { 
return elem.currentStyle[name]; 
}, 
// 获取光标在文本框的位置 
_getFocus: function (elem) { 
var index = 0; 
if (document.selection) {// IE Support 
elem.focus(); 
var Sel = document.selection.createRange(); 
if (elem.nodeName === 'TEXTAREA') {//textarea 
var Sel2 = Sel.duplicate(); 
Sel2.moveToElementText(elem); 
var index = -1; 
while (Sel2.inRange(Sel)) { 
Sel2.moveStart('character'); 
index++; 
}; 
} 
else if (elem.nodeName === 'INPUT') {// input 
Sel.moveStart('character', -elem.value.length); 
index = Sel.text.length; 
} 
} 
else if (elem.selectionStart || elem.selectionStart == '0') { // Firefox support 
index = elem.selectionStart; 
} 
return (index); 
}, 
// 获取元素在页面中位置 
_offset: function (elem) { 
var box = elem.getBoundingClientRect(), doc = elem.ownerDocument, body = doc.body, docElem = doc.documentElement; 
var clientTop = docElem.clientTop || body.clientTop || 0, clientLeft = docElem.clientLeft || body.clientLeft || 0; 
var top = box.top + (self.pageYOffset || docElem.scrollTop) - clientTop, left = box.left + (self.pageXOffset || docElem.scrollLeft) - clientLeft; 
return { 
left: left, 
top: top, 
right: left + box.width, 
bottom: top + box.height 
}; 
} 
}; 
function getPosition(ctrl) { 
var p = kingwolfofsky.getInputPositon(ctrl); 
document.getElementById('show').style.left = p.left + "px"; 
document.getElementById('show').style.top = p.bottom + "px"; 
}

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调用代码：

var elem = document.getElementById(控件ID); 
var p = kingwolfofsky.getInputPositon(elem); 
p.left;//获得指定位置坐标 
p.top;//同上 
p.bottom;//同上