lovecoding
/
VIP32


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var str = 'Happy New Year';
        // 1.toUpperCase() 将字符串中所有字母转成大写
        var str1 = str.toUpperCase();
        console.log(str1);
        // 2.toLowerCase() 将字符串中所有字母转成小写
        var str2 = str1.toLowerCase();
        console.log(str2);
        // 3.concat() 将字符串连接在一起
        var str3 = str1.concat(str2);
        console.log(str3);
        // 4.trim() 消除字符串前后的空格
        var newStr = '  hello,wor ld  ';
        var news = newStr.trim();
        console.log(newStr);
        console.log(news);
    </script>
</body>
</html>