使用JS在textarea在光标处插入内容

// 在光标处插入字符串
// myField    文本框对象
// myValue 要插入的值
function insertAtCursor(myField, myValue)
{
//IE support
if (document.selection)
{
myField.focus();
sel            = document.selection.createRange();
sel.text    = myValue;
sel.select();
}
//MOZILLA/NETSCAPE support
else if (myField.selectionStart || myField.selectionStart == '0')
{
var startPos    = myField.selectionStart;
var endPos        = myField.selectionEnd;
// save scrollTop before insert
var restoreTop    = myField.scrollTop;
myField.value    = myField.value.substring(0, startPos) + myValue + myField.value.substring(endPos, myField.value.length);
if (restoreTop > 0)
{
// restore previous scrollTop
myField.scrollTop = restoreTop;
}
myField.focus();
myField.selectionStart    = startPos + myValue.length;
myField.selectionEnd    = startPos + myValue.length;
} else {
myField.value += myValue;
myField.focus();
}
}

function insertText() {
var obj = document.getElementById("文本框");
var str = "[#$%$#]插入的内容";
if (document.selection) {
obj.focus();
var sel = document.selection.createRange();

sel.text = str;

} else if (typeof obj.selectionStart === 'number' && typeof obj.selectionEnd === 'number') {
var startPos = obj.selectionStart;
var endPos = obj.selectionEnd;
var tmpStr = obj.value;
obj.value = tmpStr.substring(0, startPos) + str + tmpStr.substring(endPos, tmpStr.length);
} else {
obj.value += str;
}
}

//jQuery光标处插入文本

$(document).ready(function () {
$("#btnInsert").click(function () {
var obj = $("#txtquestion").get(0);
var str = "[#$%$#]";
if (document.selection) {
obj.focus();
var sel = document.selection.createRange();
sel.text = str;
} else if (typeof obj.selectionStart === 'number' && typeof obj.selectionEnd === 'number') {
var startPos = obj.selectionStart;
var endPos = obj.selectionEnd;
var tmpStr = obj.value;
obj.value = tmpStr.substring(0, startPos) + str + tmpStr.substring(endPos, tmpStr.length);
} else {
obj.value += str;

});
});

(function ($) {
$.fn.insertContent = function (myValue, t) {
var $t = $(this)[0];
if (document.selection) { //ie
this.focus();
var sel = document.selection.createRange();
sel.text = myValue;
this.focus();
sel.moveStart('character', -l);
var wee = sel.text.length;
if (arguments.length == 2) {
var l = $t.value.length;
sel.moveEnd("character", wee + t);
t <= 0 ? sel.moveStart("character", wee - 2 * t - myValue.length) : sel.moveStart("character", wee - t - myValue.length);

sel.select();
}
} else if ($t.selectionStart || $t.selectionStart == '0') {
var startPos = $t.selectionStart;
var endPos = $t.selectionEnd;
var scrollTop = $t.scrollTop;
$t.value = $t.value.substring(0, startPos) + myValue + $t.value.substring(endPos, $t.value.length);
this.focus();
$t.selectionStart = startPos + myValue.length;
$t.selectionEnd = startPos + myValue.length;
$t.scrollTop = scrollTop;
if (arguments.length == 2) {
$t.setSelectionRange(startPos - t, $t.selectionEnd + t);
this.focus();
}
}
else {
this.value += myValue;
this.focus();
}
};
})(jQuery);