光标位置获取,设置,插入的操作
var cursorPosition = {
get: function (textarea) {
var rangeData = {text: "", start: 0, end: 0};
if (textarea.setSelectionRange) { // W3C 标准获取光标位置
textarea.focus();
rangeData.start = textarea.selectionStart;
rangeData.end = textarea.selectionEnd;
rangeData.text = (rangeData.start != rangeData.end) ? textarea.value.substring(rangeData.start, rangeData.end) : "";
} else if (document.selection) { // IE
textarea.focus();
var i,
oS = document.selection.createRange(),
// Don't: oR = textarea.createTextRange()
oR = document.body.createTextRange();
oR.moveToElementText(textarea);
rangeData.text = oS.text;
rangeData.bookmark = oS.getBookmark();
// object.moveStart(sUnit [, iCount])
// Return Value: Integer that returns the number of units moved.
for (i = 0; oR.compareEndPoints('StartToStart', oS) < 0 && oS.moveStart("character", -1) !== 0; i++) {
// Why? You can alert(textarea.value.length)
if (textarea.value.charAt(i) == '\r') {
i++;
}
}
rangeData.start = i;
rangeData.end = rangeData.text.length + rangeData.start;
}
return rangeData;
},
set: function (textarea, rangeData) { // 设置光标位置
var oR, start, end;
if (!rangeData) {
alert("You must get cursor position first.")
}
textarea.focus();
if (textarea.setSelectionRange) { // W3C
textarea.setSelectionRange(rangeData.start, rangeData.end);
} else if (textarea.createTextRange) { // IE
oR = textarea.createTextRange();
// Fixbug : ues moveToBookmark()
// In IE, if cursor position at the end of textarea, the set function don't work
if (textarea.value.length === rangeData.start) {
//alert('hello')
oR.collapse(false);
oR.select();
} else {
oR.moveToBookmark(rangeData.bookmark);
oR.select();
}
}
},
add: function (textarea, rangeData, text) { // 向光标位置添加内容
var oValue, nValue, oR, sR, nStart, nEnd, st;
this.set(textarea, rangeData);
if (textarea.setSelectionRange) { // W3C
oValue = textarea.value;
nValue = oValue.substring(0, rangeData.start) + text + oValue.substring(rangeData.end);
nStart = nEnd = rangeData.start + text.length;
st = textarea.scrollTop;
textarea.value = nValue;
// Fixbug:
// After textarea.values = nValue, scrollTop value to 0
if (textarea.scrollTop != st) {
textarea.scrollTop = st;
}
textarea.setSelectionRange(nStart, nEnd);
} else if (textarea.createTextRange) { // IE
sR = document.selection.createRange();
sR.text = text;
sR.setEndPoint('StartToEnd', sR);
sR.select();
}
}
}