JS基礎語法---函數練習part1---5個練習

練習1：求兩個數字的和:獲取任意的兩個數字的和

      function getSum(x, y) {
        return x + y;
      }
      console.log(getSum(10, 20));

練習2：求1-100之間所有的數字的和

      function geteverySum() {
        var sum = 0;
        for (var i = 1; i <= 100; i++) {
          sum += i;
        }
        return sum;
      }
      console.log(geteverySum());

練習3：求1-n之間所有數的和

      function geteverySum(n) {
        var sum = 0;
        for (var i = 0; i <= n; i++) {
          sum += i;
        }
        return sum;
      }
      console.log(geteverySum(89));

練習4：求n-m之間所有數的和

      function geteverySum2(n,m) {
        var sum = 0;
        for (var i = n; i <= m; i++) {
          sum += i;
        }
        return sum;
      }
      console.log(geteverySum2(32,90));

練習5：求圓的面積

      function geteverySum2(n,m) {
        var sum = 0;
        for (var i = n; i <= m; i++) {
          sum += i;
        }
        return sum;
      }
      console.log(geteverySum2(32,90));