concat拼接
和+号一样
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body><script>var str = "xiaoming"// concat连接字符串var str1 = str.concat("qqqqqqqq")console.log(str1) </script>
</body>
</html>
trim 去掉首尾空格
trimStart() trimLeft()去掉首空格
trimEnd() trimRight()去掉尾空格
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body><script>var str = " xiao ming "// trim 去掉首尾空格// trimStart() trimLeft()去掉首空格// trimEnd() trimRight()去掉尾空格console.log("|"+str+"|")console.log("|"+str.trim()+"|")console.log("|"+str.trimStart()+"|")console.log("|"+str.trimEnd()+"|")</script>
</body>
</html>
split分割
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body><script>// split 分割var str = "a,b,c,d"console.log(str.split(",")) </script>
</body>
</html>
indexOf()和lastIndexOf()
能查到返回索引位置，不存在返回-1，返回找到的第一个值的索引
indexOf()从前往后查
lastIndexOf()从后往前查
<!DOCTYPE html>
<html lang="en">
<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>Document</title>
</head>
<body><script>var str = "xiaoming"console.log(str.indexOf("i"))console.log(str.indexOf("w"))console.log(str.lastIndexOf("a"))</script>
</body>
</html>
