JavaScript-字符串常用方法
在 js 中字符串可以看做一个特殊的数组，所以大部分数组的属性 / 方法字符串都可以使用
获取字符串长度
.length
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "abcd";
console.log(str.length);
</script>
</head>
<body>
</body>
</html>
获取某个字符
[索引]/charAt
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "abcd";
let ch = str[1];
console.log(ch);
let ch2 = str.charAt(1);
console.log(ch2);
</script>
</head>
<body>
</body>
</html>
字符串查找
indexOf/lastIndexOf/includes
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "vavcd";
let index1 = str.indexOf("v");
let index2 = str.lastIndexOf("v");
console.log(index1);
console.log(index2);
let result = str.includes("d");
console.log(result);
</script>
</head>
<body>
</body>
</html>
拼接字符串
concat/+
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str1 = "www";
let str2 = "BNTang";
// 推荐
let res1 = str1 + str2;
let res2 = str1.concat(str2);
console.log(res1);
console.log(res2);
</script>
</head>
<body>
</body>
</html>
截取子串
slice/substring/substr
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "abcdef";
let subStr1 = str.slice(1, 3);
let subStr2 = str.substring(1, 3);
let subStr3 = str.substr(1, 3);
console.log(subStr1);
console.log(subStr2);
console.log(subStr3);
</script>
</head>
<body>
</body>
</html>
字符串切割
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let arr1 = [1, 3, 5];
let str1 = arr1.join("-");
console.log(str1);
let str2 = "1-3-5";
let arr2 = str2.split("-");
console.log(arr2);
</script>
</head>
<body>
</body>
</html>
ES6
判断是否以指定字符串开头
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "https://www.cnblogs.com/BNTang";
let result = str.startsWith("www");
console.log(result);
</script>
</head>
<body>
</body>
</html>
判断是否以指定字符串结尾
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str = "BNTang.png";
let result = str.endsWith("png");
console.log(result);
</script>
</head>
<body>
</body>
</html>
字符串模板
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Demo</title>
<script>
let str1 = "";
let str2 = '';
let str3 = `https://www.cnblogs.com/BNTang`;
console.log(typeof str3);
let str4 = `<ul>
<li>我是第1个li</li>
<li>我是第2个li</li>
<li>我是第3个li</li>
</ul>`;
console.log(str4);
let name = "BNTang";
let age = 34;
// let str = "我的名字是：" + name + ",我的年龄是：" + age;
let str5 = `我的名字是：${name},我的年龄是：${age}`;
console.log(str5);
</script>
</head>
<body>
</body>
</html>
