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console 命令行工具 X clear

                    
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console
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script>
// 计算1+2+3 ... +98+99+100的值

//1 .for循环
function sum_all() {
var result = 0;
for (var i = 0; i <= 100; i++) {
result += i;
}
return result
}

var s = sum_all();

alert(s);
// 2. do-while语句
// 后测试循环语句
function sum_all3() {
var result3 = 0;
var i = 0;
do {

result3 += i;
i++;
}
while (i <= 100);

return result3
}

alert(sum_all3())
//3. while()循环

function sum_all2() {
var result2 = 0;
var i = 0;
while (i <= 100) {

result2 += i;
i++;
}
return result2
}

alert(sum_all2());


</script>
</body>
</html>