Node.js 读取远程文件

readRemoteFile.js

var http = require('http');

/**
 * 读取远程文件
 *
 * @param {String} url
 * @param {Function} cb
 *   - {Error} err
 *   - {Buffer} buf
 */
function readRemoteFile (url, cb) {
  var callback = function () {
    // 回调函数，避免重复调用
    callback = function () {};
    cb.apply(null, arguments);
  };

  var req = http.get(url, function (res) {
    var b = [];
    res.on('data', function (c) {
      b.push(c);
    });
    res.on('end', function () {
      callback(null, Buffer.concat(b));
    });
    res.on('error', callback);
  });
  req.on('error', callback);
}

readRemoteFile('http://www.baidu.com/img/bdlogo.gif', function (err, buffer) {
  if (err) throw err;
  console.log(buffer.length, buffer);
});