實(shí)例演示四種常用的函數(shù)類型

<script>
      // 命名函數(shù)
      let r = 8;
      const PI = 3.14;
      console.log(square(r));
      function square(radio) {
        return (
          `命名函數(shù)計(jì)算半徑為${radio}cm 的圓形面積為 ` +
          PI * radio * radio +
          ` cm^2`
        );
      }
      // 匿名函數(shù)
      let square1 = function (r) {
        return `匿名函數(shù)計(jì)算半徑為${r}cm 的圓形面積為 ` + PI * r * r + ` cm^2`;
      };
      console.log(square1(5));
      // 箭頭函數(shù)
      let square2 = (r) => {
        return `箭頭函數(shù)計(jì)算半徑為${r}cm 的圓形面積為 ` + PI * r * r + ` cm^2`;
      };
      console.log(square2(9));
      // 立即執(zhí)行函數(shù)
      let square3 = (function () {
        return (
          `立即執(zhí)行函數(shù)計(jì)算半徑為${r}cm 的圓形面積為 ` + PI * r * r + ` cm^2`
        );
      })(12);
      console.log(square3);
    </script>

實(shí)際演示原始數(shù)據(jù)類型與引用類型

      let uname = "mike";
      let age = 28;
      let gender = null;
      let mail;
      let student = [uname, age, gender, mail];
      console.table(student);
      let workmate = { name: uname, age: age, gender: gender, mail: mail };
      console.dir(workmate);
      let ismale = workmate.gender == "male";
      console.log(
        workmate.name +
          "'s age is " +
          workmate["age"] +
          ". gender is male? " +
          ismale
      );

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