Node js covert string字符集

Question

我需要将输入的值转换为所选字符集的值。1：https://i.stack.imgur.com/vh07r.png我的代码：

    const express = require('express');
const app = express();
const path = require('path');
var bodyParser = require('body-parser');
var iconv = require('iconv-lite');


var urlencodedParser = bodyParser.urlencoded({ extended: false });


app.get('/', function(req, res) {
    res.sendFile(path.join(__dirname, '/index.html'));
});

app.post('/',urlencodedParser, function(req, res) {
    let input = req.body.input;
    let select = req.body.select;
    let utf8 = iconv.encode(input, 'utf-8');
    let iso = iconv.encode(input, 'iso-8859-1');
    let win = iconv.encode(input, 'win1252');
    console.log(utf8.toString());
    console.log(iso.toString());
    console.log(win.toString());

    
    res.sendFile(path.join(__dirname, '/index.html'));
    res.send(`Input string <textarea character-set=>${input}</textarea><br>
    ISO <textarea character-set="ISO-8859-1"></textarea><br>
    UTF-8 <textarea character-set="UTF-8"></textarea><br>
    Win-1252 <textarea character-set="windows-1252"></textarea><br>
    `); 
});

app.listen(3000);

Answer 1

假设您想使用位于path.join(__dirname, '/index.html')的文件内容作为模板，您可以将编码转换的结果注入其中？

如果是这样的话，一个简单的解决方案是：

const { format } = require('util');

const sourceFilepath = path.join(__dirname, '/index.html');

// Load the html source you wish to return as the result.
// Note that if the file cannot be read, this will throw an 
// exception on server start.
const content = fs.readSync(sourceFilepath);

// The content of content should include a textarea tag in the 
// following format: 
//   `<textarea character-set="%s">%s</textarea>';` 
// where the selected encoding will replace the first `%s` and 
// the resulting encoded input text will replace the second.

// Helper to report errors back to the caller
const reportError = (res, message) => {
  res.status(500).send(message);
  res.end();
};

// Helper to ensure we have a string to encode.
const isNonEmptyString = (s) => (typeof s === 'string') && s.length;

app.post('/', urlencodedParser, function(req, res) {

  // ensure we have something to encode 
  // (trimming leading and trailing spaces.)
  const src = req.body.input.trim();

  if (!isNonEmptyString(src)) {
    reportError(res, 'requires some input to encode');
    return;
  }

  // set the required encoding, using utf-8 as a fall-back.
  const encoding = req.body.select || 'UTF-8';

  // encode the src using the encoding
  // in the case of an encoding error, return a reasonable error message
  // to the caller.

  let result;
  try {
    result = iconv.encode(src, encoding);
  } catch (err) {
    reportError(`Error: failed to convert src using encoding "${encoding}": ${err}`);
    return;
  }
  
  // send back the result after replacing the printf `%s` markers with the
  // selected encoding and the transformed src
.
  res.send(format(content, encoding, result));
  res.end();
});

请注意，这只是一个完整解决方案的开始，但这里应该有足够的内容让您入门。

有许多方法可以进行所需的转换，将结果流式传输回调用者会更有效，但这是最简单的解决方案。

两种风格的注释：

1. Javascript提供了三种定义变量的方法：var、let和const，了解每种方法特定用途的原因是很重要的。仅使用let有可能在代码中注入难以调试的错误。
2. 为提高可靠性，请始终包装可能在try/catch中引发异常的操作，并始终适当地处理捕获的异常。如果不这样做，您将面临无法向调用者返回任何内容的风险，这也会使调试代码变得困难。