js-循环-计算1+2+3 ... +98+99+100的值
<!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 // 前测试循环 function sum_all() { var result = 0; for (var i = 0; i <= 100; i++) { result += i; } return result } var s = sum_all(); alert(s); //2. while()循环 // 前测试循环 function sum_all2() { var result2 = 0; var i = 0; while (i <= 100) { i++; result2 += i; } return result2 } alert(sum_all2()); // do-while语句 // 后测试循环语句 function sum_all3() { var result3 = 0; var i = 0; do { i++; result3 += i; } while (i <= 100); return result3 } alert(sum_all3()) </script> </body> </html>