js-jQuery-jQueryLoader-检查$是否未定义，如果需要，用纯javascript加载jQuery

Posted 2021-02-25

/* I used to use (!$) or ($ == undefined) but that doesn't work sucka! */
 
if (!window.jQuery) {
	var jqscript = document.createElement('script');
	jqscript.setAttribute("type", "text/javascript");
	jqscript.setAttribute("src", "http://code.jquery.com/jquery.min.js");
	document.getElementsByTagName("head")[0].appendChild(jqscript);
};