js map(Number) map(String) map(Boolean) 转换类型详解

      // 1.将字符串数组转化为数值型数组
      let strArr = ["1", "2", "3"];
      strArr.map(Number); // [1,2,3]  Number自动转换为number函数并把值传进去

      // 2.将数值型数组转化为字符串数组
      let numArr = [1, 2, 3];
      numArr.map(String); //  ["1", "2", "3"]

      // 3.将数值型数组转换为布尔值
      let numArr = [0, 1, 0, 1, 1];
      numArr.map(Boolean); // [false,true,false,true,true]

      // 4.混合类型也可以转换
      let newArr = [1, "2", "3", 4, 5];

      newArr.map(Boolean); // [true,true,true,true,true]
      newArr.map(String); //  ["1", "2", "3","4","5"]
      newArr.map(Number); //  [1,2,3,4,5]