SOURCE

// 第三题
var count1=0;
var num=0;
while(num<100){
num++;
count1+=num;

}

document.write(count1+"<br>")
 count1=0;
 num=0;

do{
num++;
  count1+=num;
}while(num<100);

document.write(count1+"<br>")

 count1=0;
for(i=1; i<=100;i++){
    count1+=i;
}
document.write(count1+"<br>")