insertAtCaret
は jQuery の拡張であり、通常は含まれていません。extensionを追加すると、次のように機能します。
デモ
$.fn.insertAtCaret = function(myValue) {
return this.each(function() {
var me = this;
if (document.selection) { // IE
me.focus();
sel = document.selection.createRange();
sel.text = myValue;
me.focus();
} else if (me.selectionStart || me.selectionStart == '0') { // Real browsers
var startPos = me.selectionStart, endPos = me.selectionEnd, scrollTop = me.scrollTop;
me.value = me.value.substring(0, startPos) + myValue + me.value.substring(endPos, me.value.length);
me.focus();
me.selectionStart = startPos + myValue.length;
me.selectionEnd = startPos + myValue.length;
me.scrollTop = scrollTop;
} else {
me.value += myValue;
me.focus();
}
});
};