如何使用javascript编辑文本文件的特定行

// 1. 读取文本文件
function readFile(file) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    
    reader.onload = (event) => {
      resolve(event.target.result);
    };
    
    reader.onerror = (event) => {
      reject(event.target.error);
    };
    
    reader.readAsText(file);
  });
}

// 2. 编辑特定行
function editSpecificLine(text, lineNumber, replacement) {
  const lines = text.split('\n');
  
  if (lineNumber >= 0 && lineNumber < lines.length) {
    lines[lineNumber] = replacement;
  }
  
  return lines.join('\n');
}

// 3. 写入文件
function writeFile(file, text) {
  return new Promise((resolve, reject) => {
    const writer = new FileWriter();
    
    writer.onwriteend = (event) => {
      resolve();
    };
    
    writer.onerror = (event) => {
      reject(event.target.error);
    };
    
    writer.write(text);
  });
}

// 例子使用
const fileInput = document.getElementById('file-input');
const lineNumberInput = document.getElementById('line-number-input');
const replacementInput = document.getElementById('replacement-input');

fileInput.addEventListener('change', async (event) => {
  const file = event.target.files[0];
  
  try {
    const text = await readFile(file);
    const lineNumber = parseInt(lineNumberInput.value);
    const replacement = replacementInput.value;
    
    const newText = editSpecificLine(text, lineNumber, replacement);
    
    await writeFile(file, newText);
    
    console.log('文件已编辑');
  } catch (error) {
    console.error('编辑文件时出错', error);
  }
});