微博添加话题组件

jquery.topic.js

(function($) {
  $.fn.topic = function(options) {
    var opts = $.extend({}, $.fn.topic.defaults, options);
    return this.each(function() {
		var $this = $(this),rangeLength = opts.text.length + 1;
		$(opts.btn).click(function(){
			$this.focus().val("#"+opts.text+"#");
			if($.browser.msie){
				var range = $this[0].createTextRange();
				var sel = range.duplicate();
				range.move("character",1);
				sel.moveStart("character", rangeLength);
				sel.setEndPoint("EndToStart", range);
				sel.select();
			}else{
				$this[0].selectionStart = 1;
				$this[0].selectionEnd = rangeLength;	
			}
		});
    });
  };
  // plugin defaults
  $.fn.topic.defaults = {
	text: '请输入你的话题',
	btn:"#btn"
  };
})(jQuery);
//example below:
$("#post").topic({btn:"#btn",text:"随便说点设么吧"})