js 光标位置处理

 ?/**
 ??* 获取选中文字
 ??* 返回selection,toString可拿到结果,selection含有起始光标位置信息等
 ??**/ ?function getSelectText() { ?????var text, ?????????userSelection = window.getSelection()||document.selection.createRange();// not IE || ie ?????if (!(text = userSelection.text)) text = userSelection; ?????return text; ?} ?/**
 ??* 获取光标位置
 ??* 对 input、textarea有效，对contenteditable:true方式不生效
 ??**/ ?function getCursortPosition (textDom) { ???var cursorPos = 0; ???if (document.selection) { ???????// IE Support ???????textDom.focus (); ???????var selectRange = document.selection.createRange(); ???????selectRange.moveStart (‘character‘, -textDom.value.length); ???????cursorPos = selectRange.text.length; ???}else if (textDom.selectionStart || textDom.selectionStart == ‘0‘) { ???????// 非 IE ???????cursorPos = textDom.selectionStart; ???} ???return cursorPos; ?} ?/**
 ??* 设置光标位置
 ??* 有效对象同光标获取
 ??**/ ?function setCaretPosition(textDom, pos){ ?????if(textDom.setSelectionRange) { ?????????// IE Support ?????????textDom.focus(); ?????????textDom.setSelectionRange(pos, pos); ?????}else if (textDom.createTextRange) { ?????????// 非 IE ?????????var range = textDom.createTextRange(); ?????????range.collapse(true); ?????????range.moveEnd(‘character‘, pos); ?????????range.moveStart(‘character‘, pos); ?????????range.select(); ?????} ?}