<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
/* 强转 */
/* 1.其他类型转为Number类型 */
var s1 = "10";
var s2 = "abc";
var b1 = false;
var o1 = Object(10);
var o2 = new Array();
o2[0]=1;
o2[1]=2;
var o3 = null;
document.write("String转number，可转："+Number(s1)+"<br>");//10
document.write("String转number，不可转："+Number(s2)+"<br>");//Nan
document.write("boolean转number，可转："+Number(b1)+"<br>");//0
document.write("Object转number=："+Number(o2)+"<br>");//若o2中只有o2[0]，则为1，若还有o2[1]，则为NaN
document.write("null转number："+Number(o3)+"<br>");//0
/* 能转就转，不能转就为NaN， */
/* 2.其他类型转为boolean类型 */
var nb = 10;
var sb = "abc";
var ob = new Object(1);
var unb;
//2.1Number转Boolean
document.write("Number转Boolean："+Boolean(nb)+"<br>");//非零转成true，0转成false
//2.2String转Boolean
document.write("String转Boolean："+Boolean(sb)+"<br>");//非空转成true，空转成false
//2.3Object转Boolean
document.write("Object转Boolean："+Boolean(ob)+"<br>");//非null转成true，null转成false
//2.4声明未赋值(undefined)转Boolean
document.write("声明未赋值(undefined)转Boolean："+Boolean(unb)+"<br>");//false
</script>
</head>
<body>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script type="text/javascript">
/* 3.boolean转String */
var b = true;
document.write("Boolean转String："+typeof(b.toString())+"<br>");//String
/* 4.String转Number */
var s = "10";
document.write("String转Number："+typeof(parseInt(s) )+"<br>");//number
</script>
</head>
<body>
</body>
</html>
