动态加载js和css

// 动态加载外部js文件
var flag = true;
if( flag ){
	loadScript( "js/index.js" );
};
function loadScript( url ){
	var script = document.createElement( "script" );
	script.type = "type/javascipt";
	script.src = url;
	document.getElementsByTagName( "head" )[0].appendChild( script );
};

// 动态加载js
if( flag ){
	var script = document.createElement( "script" );
	script.type = "text/javascript";
	script.text = " ";
	document.getElementsByTagName( "head" )[0].appendChild( script );
};

// 动态加载外部css样式
if( flag ){
	loadCss( "css/base.css" );
};
function loadCss( url ){
	var link = document.createElement( "link" );
	link.type = "text/css";
	link.rel = "stylesheet";
	link.href = url;
	document.getElementsByTagName( "head" )[0].appendChild( link );
};

// 动态加载css样式
if( flag ){
	var style = document.createElement( "style" );
	style.type = "text/css";
	document.getElementsByTagName( "head" )[0].appendChild( style );
	var sheet = document.styleSheets[0];
	insertRules( sheet,"#gaga1","background:#f00",0 );
};
function insertRules( sheet,selectorTxt,cssTxt,position ){
	if( sheet.insertRule ){ // 判断非IE浏览器
		sheet.insertRule( selectorTxt + "{" + cssTxt +"}" ,position );
	}else if( sheet.addRule ){ //判断是否是IE浏览器
		sheet.addRule( selectorTxt ,cssTxt ,position )
	}
}