JavaScript获取光标的位置

(function($) {
		$.fn.extend({
			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);

调用：$("#target").insertContent(content);