SOURCE

function hanshu(firstname,lastname){
	// var k = fanhui();
	// document.getElementById('kk').innerHTML = k;
  document.getElementById('kk').innerHTML = fanhui();
}

// function fanhui(){
//   var x = '龙敏';
//   return x;
// }



function myfunction(){
	// 数组
	/*var x = new Array();
	x[0] = 1;
	x[1] = 2;
	x[2] = 3;
	x[3] = 4;
	alert(x.length);*/
	
	/*var y = new Array('a','b','c','d');
	alert(y + ';' + y.length);*/
	
	/*var z = ['q','w','e'];
	alert(z + ";" + z.length);*/
	
	
	// 对象
	/*var person = {"firstname":"long","lastname":"min","id":"15796"};
	document.getElementById("ff").innerHTML = person.firstname + "," + person.lastname + "," +person.id;
	document.getElementById('dd').innerHTML= person['firstname'] + "," +person['lastname'] + "," + person['id'];*/
	
	// null 清空变量
	/*var cart = '1200';
	alert(cart);
	var cart = null;
	alert(cart);*/
	
	// new 声明变量类型
	/*var x = new String;
	var y = new Number;
	var z = new Boolean;
	var t = new Array;
	var b = new Object;*/

	// 对象
	// var txt = 'Visit W3School!';
	// alert(txt.length);
	// alert(txt.indexOf('o'));  //字符首次出现位置
	// alert(txt.search(/sit/));
	// document.write(txt.replace(/Hello/,'world'));  //替换
	// document.write(txt.toUpperCase());  //字符串转换为大写
	
}

<button onclick="myfunction()">点击这里</button>
<span id="ff"></span>
<span id="dd"></span>
<button onclick="hanshu('long','min')">函数</button>
<button onclick="fanhui()">返回值</button>
<p id="kk"></p>

#ff,#dd,h1,h2,h3,h4,h5,h6,#kk{color:#fff;}