How to perform case conversion operation in nodejs

Node.js is an open source, cross-platform JavaScript runtime environment that executes JavaScript on the server side. Its simple, easy-to-learn, lightweight, and efficient features make it widely used in a variety of application scenarios.

This article will introduce how to perform case conversion operation. In the usual programming process, we often encounter situations where we need to convert the upper and lower case of strings. Through the methods in Node.js, we can implement this function quickly and conveniently.

First we need to understand a few methods:

• toUpperCase(): Convert the string to uppercase letters.
• toLowerCase(): Convert the string to lowercase letters.

Next, we will demonstrate the use of these two methods through examples.

// 将字符串转换为大写字母
let str1 = 'hello node.js';
let upperCaseStr = str1.toUpperCase();
console.log(upperCaseStr); // 输出：HELLO NODE.JS

// 将字符串转换为小写字母
let str2 = 'HELLO NODE.JS';
let lowerCaseStr = str2.toLowerCase();
console.log(lowerCaseStr); // 输出：hello node.js

The above code demonstrates how to use these two methods to convert string case. The method returns a new string after conversion, and the original string remains unchanged.

In addition to using the above method, we can also use regular expressions to convert uppercase and lowercase letters. The specific method is as follows:

// 将字符串转换为大写字母
let str3 = 'hello node.js';
let upperCaseStr2 = str3.replace(/[a-z]/g, function(s) {
    return String.fromCharCode(s.charCodeAt(0) - 32);
});
console.log(upperCaseStr2); // 输出：HELLO NODE.JS

// 将字符串转换为小写字母
let str4 = 'HELLO NODE.JS';
let lowerCaseStr2 = str4.replace(/[A-Z]/g, function(s) {
    return String.fromCharCode(s.charCodeAt(0) + 32);
});
console.log(lowerCaseStr2); // 输出：hello node.js

The above code uses regular expressions and uses the replace() method to achieve case conversion. The specific method is to replace all lowercase letters in the string to be converted with corresponding uppercase letters, and replace all uppercase letters with corresponding lowercase letters. Among them, the String.fromCharCode() method can convert numbers into corresponding ASCII characters.

In addition to using regular expressions, we can also use the Buffer type method to achieve case conversion.

// 将字符串转换为大写字母
let str5 = 'hello node.js';
let buffer = Buffer.from(str5, 'utf-8');
let upperCaseBuffer = buffer.toString('utf-8').toUpperCase();
console.log(upperCaseBuffer); // 输出：HELLO NODE.JS

// 将字符串转换为小写字母
let str6 = 'HELLO NODE.JS';
let buffer2 = Buffer.from(str6, 'utf-8');
let lowerCaseBuffer = buffer2.toString('utf-8').toLowerCase();
console.log(lowerCaseBuffer); // 输出：hello node.js

The above code uses the Buffer type method to achieve case conversion. The specific method is to convert the string into a Buffer, then use the toString() method of the Buffer object to convert it to a string, and use the toUpperCase() and toLowerCase() methods to convert the case of the string.

The above is how to implement case conversion in Node.js. Through the above method, the case of a string can be easily converted to meet various programming needs.

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