字符串和数组常用API

字符串和数组常用API

字符串API

<script>
      // 字符串
      let str = "ABc,123上学去";
      //   长度
      console.log(str.length);
      // 索引
      //   索引->元素
      console.log(str[8]);
      console.log(str.charAt(8));
      //   元素->索引
      console.log(str.indexOf("上"));
      console.log(str.search("去"));
      //   拼装
      console.log(str.concat("啦啦啦"));
      console.log(str + "哈哈哈");
      console.log(`${str}嘻嘻嘻`);
      // 替换replace
      console.log(str.replace("123", "我"));
      document.body.append(str.replace("123", "我"));
      //   取子串
      console.log(str.slice(1, 7));
      //   知道取几个
      console.log(str.substr(3, 4));
      // 从后边取
      console.log(str.substr(-4, 4));
      //   变大写或者变小写
      console.log(str.toLowerCase());
      console.log(str.toUpperCase());
      //   加a链接
      console.log(str.link("https://baidu.com"));
      document.body.insertAdjacentHTML(
        "afterBegin",
        str.link("https://baidu.com")
      );
      // 加粗
      console.log(str.bold());
      //   document.body.append(str.bold());
      document.body.insertAdjacentHTML("afterBegin", str.bold());
    </script>

数组API

<script>
      //   数组
      //   字面量
      let arr = [
        1,
        3,
        4,
        "我",
        function () {
          return 1;
        },
        { x: 0.2, y: 0.5 },
      ];
      console.log("-----------------------------");
      console.log(arr);
      console.log(Array.of(...arr));
      // 类数组
      let jon = {
        0: "x",
        1: "y",
        2: "z",
        length: 3,
      };
      console.log(Array.from(jon));
      //   数组两端增删
      //   push\pop\unshift\shift
      const myArray = [1, 5, 78, 34, 67, 99];
      //查找
      //   filter find findIdex;
      console.log(
        myArray.filter(function (item) {
          return item >= 20;
        })
      );
      console.log(myArray.find((item) => item >= 20));
      console.log(myArray.findIndex((item) => item >= 20));
      //   归并reduce
      res = myArray.reduce(function (acc, item, index, myArray) {
        return acc + item;
      }, 100);
      console.log(res);
      //遍历
      let arr1 = myArray.forEach(
        (item, index, arr) => (arr[index] = item * 10)
      );
      console.log(arr1);
      console.log(myArray);
      let arr2 = myArray.map((item) => item * 2);
      console.log("-------------------");
      console.log(arr2);
      console.log(myArray);
      //正序反序排列sort
      console.log(myArray.sort((a, b) => a - b));
      console.log(myArray.sort((a, b) => b - a));
      //   数组转字符串toString
      // 数组的slice
      console.log(myArray.slice(1, 4));
      //   删除新增替换splice
      // 默认删除
      console.log(myArray.splice(1, 2));
      console.log(myArray);
      // 新增
      console.log(myArray.splice(1, 0, "张先生"));
      console.log(myArray);
      // 替换
      console.log(myArray.splice(1, 1, "李先生"));
      console.log(myArray);
    </script>