function removeExtension(filename) {
    // 方法1: 使用lastIndexOf和substring
    const lastDot = filename.lastIndexOf('.');
    return lastDot === -1 ? filename : filename.substring(0, lastDot);
    
    // 方法2: 使用正则表达式
    // return filename.replace(/\.[^/.]+$/, "");
}

// 使用示例
const originalName = "document.pdf";
const newName = removeExtension(originalName); // "document"

const path = require('path');

function removeExtension(filename) {
    return path.parse(filename).name;
}

console.log(removeExtension('image.jpg')); // 输出: image

import os

def remove_extension(filename):
    return os.path.splitext(filename)[0]

print(remove_extension("report.docx"))  # 输出: report

function removeExtension($filename) {
    return pathinfo($filename, PATHINFO_FILENAME);
}

echo removeExtension("presentation.pptx"); // 输出: presentation

public class Main {
    public static String removeExtension(String filename) {
        int lastDot = filename.lastIndexOf('.');
        return lastDot == -1 ? filename : filename.substring(0, lastDot);
    }
    
    public static void main(String[] args) {
        System.out.println(removeExtension("data.json")); // 输出: data
    }
}