异常 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>5-11</title>
</head>
<body>
<script language="javascript">
try
{
    var n = error;          // 人为引发一个错误
}
catch( e )            
{
    alert( (e.number&0xFFFF) + "号错误：" + e.description );// 错误处理：仅输出错误信息
}
</script>
</body>
</html>

out

 

 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>5-12</title>
</head>
<body>
<script language="javascript">
try
{
    var fruit = new Array( "鸭梨", "苹果", "葡萄", "李子" );    // 水果
    for( n=0; n<fruit.length; m++ )                             // 遍历数组，在此人为引发一个异常
    {
        document.write( fruit[n] + " " );
    }
}
catch( e )            
{
    alert( (e.number&0xFFFF) + "号错误：" + e.description );    // 处理异常
}
finally                                                         // finally块中清除数组所占的资源
{
    fruit = null;
    alert( "fruit="+fruit+"已经断开fruit数组的引用！");
}
</script>
</body>
</html>

除数为0异常

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>5-13</title>
</head>
<body>
<script language="javascript">
try
{
    var total = 100;
    var parts = 0;
    if( parts == 0 )                    // 如果除数为0则抛出异常
    {
        throw "Error:parts is zero";
    }
    alert( "每人"+total/parts+"份");    //此处将捕获try块中抛出的异常
}
catch( e )
{
    alert( e );
}
</script>
</body>
</html>

 

posted on 2017-08-09 22:28  huodaihao  阅读(138)  评论(0)  编辑  收藏  举报

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