求助一下这段代码中sum.arguments.length是个什么函数?<html><body><script>
function sum(StartVal,EndVal)
{
var ArgNum = sum.arguments.length;
var i,s=0;
if (ArgNum == 0 )
{ StartVal = 1; EndVal = 1000; }
else if (ArgNum == 1 )
EndVal = 1000;
for (i = StartVal; i<=EndVal; i++)
s+=i;
return s;
}
document.write("不给出参数调用函数sum:",sum(),"<br>");
document.write("给出一个参数调用函数sum:",sum(500),"<br>");
document.write("给出二个参数调用函数sum:",sum(1,50),"<br>");
</script></body></html>
function sum(StartVal,EndVal)
{
var ArgNum = sum.arguments.length;
var i,s=0;
if (ArgNum == 0 )
{ StartVal = 1; EndVal = 1000; }
else if (ArgNum == 1 )
EndVal = 1000;
for (i = StartVal; i<=EndVal; i++)
s+=i;
return s;
}
document.write("不给出参数调用函数sum:",sum(),"<br>");
document.write("给出一个参数调用函数sum:",sum(500),"<br>");
document.write("给出二个参数调用函数sum:",sum(1,50),"<br>");
</script></body></html>
arguments是Function()对象的属性,表示函数的参数数组,数组中包含了每个传递过来的参数
arguments.length就是数组的长度,即参数的个数