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<!DOCTYPE html><html lang="zh-CN"><head><meta charset="UTF-8" /><meta http-equiv="X-UA-Compatible" content="IE=edge" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><title>字符串api和数组api实例演示</title></head><body><script>let xu = "许可可博客";//获取字符串长度console.log(xu.length);//按照索引方式获取字符元素'可'console.log(xu[2]);//按照元素方式获取索引值console.log(xu.indexOf("可"));//从某个位置开始取几个字符 支持负数 也就是从后往前取console.log(xu.substr(1, 3)); //从索引[1]开始取3个// 字符串替换 必须要相邻的字符 前面是被替换的后面是替换后的console.log(xu.replace("许可", "xukeke"));//数组//数组的两种遍历方式let arr = [1, 2, 3, 4, 5, 6, 7, 8];console.log(arr.length);// forEach方法let res = arr.forEach((itme, index, arr) =>console.log(itme, index, arr));console.log(res);// map方法res2 = arr.map((itme) => itme * 5);console.log(res2);//every:全部满足条件就返回tureconsole.log(arr.every((itme) => itme >= 0));console.log(arr.every((itme) => itme >= 2));// some：只有有一个满足条件就返回tureconsole.log(arr.some((itme) => itme >= 7));console.log(arr.some((itme) => itme >= 2));//返回符合条件的第一个元素 findconsole.log(arr.find((itme) => itme >= 9));console.log(arr.find((itme) => itme >= 8));</script></body></html>
