为什么我在运行下面显示的代码时会出错？ (它用于 Coursera 上斯坦福“创业工程”类(class)的作业之一:https://class.coursera.org/startup-001/quiz/attempt?quiz_id=149)

该类(class)于 2013 年 6 月至 9 月开课，因此可能存在破坏脚本的 Node 或 csv 更新，对吧？作业不是关于修复脚本的，所以这个问题不是'作弊'，而且类(class)目前没有运行..

所以，环境是: Ubuntu 14.04(内核 3-13-0-29-generic)， Node v0.11.13， npm v1.4.9

我在主目录中有 npm install 的 csv、accounting util 和 reSTLer，脚本也在那里。

这让我完全难住了.... :-(

错误信息:

[ubuntu@ip-xxx-xxx-xxx-xxx:~]$node market-research.js
Invoked at command line.
Wrote market-research.csv
Symbol  Name    Market Cap      Previous Close Price    P/E Ratio       Shares  EPS   Earnings
/home/ubuntu/market-research.js:47
    csv()
    ^
TypeError: object is not a function
    at csv2console (/home/ubuntu/market-research.js:47:5)
    at Request.response2console (/home/ubuntu/market-research.js:65:13)
    at Request.EventEmitter.emit (events.js:110:17)
    at Request.mixin._fireSuccess (/home/ubuntu/node_modules/restler/lib/restler.js:226:10)
    at /home/ubuntu/node_modules/restler/lib/restler.js:158:20
    at IncomingMessage.parsers.auto (/home/ubuntu/node_modules/restler/lib/restler.js:394:7)
    at Request.mixin._encode (/home/ubuntu/node_modules/restler/lib/restler.js:195:29)
    at /home/ubuntu/node_modules/restler/lib/restler.js:154:16
    at Request.mixin._decode (/home/ubuntu/node_modules/restler/lib/restler.js:170:7)
    at IncomingMessage.<anonymous> (/home/ubuntu/node_modules/restler/lib/restler.js:147:14)
[ubuntu@ip-xxx-xxx-xxx-xxx:~]$

代码:

    #!/usr/bin/env node
    /*
    Use the Yahoo Finance CSV API to do some basic market research calculations.

     - Background: http://greenido.wordpress.com/2009/12/22/yahoo-finance-hidden-api/
     - Example URL: http://finance.yahoo.com/d/quotes.csv?s=GOOG+FB+AAPL&f=snj1pr
        s:  Symbol
        n:  Name
        j1: Market Capitalization (in billions)
        p:  Price-per-share (at previous close)
        r:  Price to Earnings Ratio

    Further references.

     - https://github.com/danwrong/restler
     - https://github.com/wdavidw/node-csv
     - http://josscrowcroft.github.io/accounting.js
     - http://stackoverflow.com/questions/4981891/node-js-equivalent-of-pythons-if-name-main
     - http://nodejs.org/docs/latest/api/util.html#util_util_format_format

    */

    var util = require('util');
    var fs = require('fs');
    var rest = require('restler');
    var csv = require('csv');
    var accounting = require('accounting');
    var CSVFILE_DEFAULT = "market-research.csv";
    var SYMBOLS_DEFAULT = ["GOOG", "FB", "AAPL", "YHOO", "MSFT", "LNKD", "CRM"];
    var COLUMNS_DEFAULT = 'snj1pr'; // http://greenido.wordpress.com/2009/12/22/yahoo-finance-hidden-api
    var HEADERS_DEFAULT = ["Symbol", "Name", "Market Cap", "Previous Close Price", 
                           "P/E Ratio", "Shares", "EPS", "Earnings"];

    var financeurl = function(symbols, columns) {
        return util.format(
            'http://finance.yahoo.com/d/quotes.csv?s=%s&f=%s',
            symbols.join('+'),
            columns);
    };

    var marketCapFloat = function(marketCapString) {
        return parseFloat(marketCapString.split('B')[0]) * 1e9;
    };

    var csv2console = function(csvfile, headers) {
        console.log(headers.join("\t"));
        csv()
        .from.path(csvfile)
        .on('record', function(row, index) {
            var shares = Math.round(marketCapFloat(row[2])/row[3], 0);
            var eps = (row[3]/row[4]).toFixed(3);
            var earnings = accounting.formatMoney(eps * shares);
            outrow = row.concat([shares, eps, earnings]);
            console.log(outrow.join("\t"));
        });
    };

    var buildfn = function(csvfile, headers) {
        var response2console = function(result, response) {
            if (result instanceof Error) {
                console.error('Error: ' + util.format(response.message));
            } else {
                console.error("Wrote %s", csvfile);
                fs.writeFileSync(csvfile, result);
                csv2console(csvfile, headers);
            }
        };
        return response2console;
    };

    var marketResearch = function(symbols, columns, csvfile, headers) {
        symbols = symbols || SYMBOLS_DEFAULT;
        columns = columns || COLUMNS_DEFAULT;
        csvfile = csvfile || CSVFILE_DEFAULT;
        headers = headers || HEADERS_DEFAULT;
        var apiurl = financeurl(symbols, columns);
        var response2console = buildfn(csvfile, headers);
        rest.get(apiurl).on('complete', response2console);
    };

    if(require.main == module) {
        console.error('Invoked at command line.');
        var symbols = process.argv;
        if(symbols.length > 2) {
            symbols = symbols.slice(2, symbols.length);
        } else {
            symbols = undefined;
        };
        marketResearch(symbols);
    } else {
        console.error('Invoked via library call');
    }

    exports.marketResearch = marketResearch;

脚本创建的market-research.csv内容:

    "GOOG","Google Inc.",386.6B,569.20,29.49
    "FB","Facebook, Inc.",194.5B,73.855,78.49
    "AAPL","Apple Inc.",613.8B,102.25,16.49
    "YHOO","Yahoo! Inc.",38.302B,38.31,33.11
    "MSFT","Microsoft Corpora",374.3B,44.88,17.06
    "LNKD","LinkedIn Corporat",27.747B,223.26,N/A
    "CRM","Salesforce.com In",36.577B,58.29,N/A

最佳答案

Quantas 94 Heavy，感谢提示。

12 个月前，node-csv 的版本是 0.2，但现在是 0.4，API 也发生了变化。

我现在编写的 csv-console 函数如下:

// part of file market-script.js
// edited by Jeff Moye (Moyesoft)
// no attribution in the original file

var csv2console = function(csvfile, headers) {
  console.log(headers.join("\t"));
  var parser = csv.parse();    //create the parser                                                                                                            

  parser.on('readable', function(){    //the 'record' event no longer exists                                                                                  
                                       // so instead we write a handler for the                                                                               
                                       // 'readable' event                                                                                                    
    while(record = parser.read()){     // and read() each record in a loop                                                                                                                  
      var shares = Math.round(marketCapFloat(record[2])/record[3], 0);
      var eps = (record[3]/record[4]).toFixed(3);
      var earnings = accounting.formatMoney(eps * shares);
      outrow = record.concat([shares, eps, earnings]);
      console.log(outrow.join("\t"));
    }
  });

  parser.on('error', function(err){    // we may as well have an error handler                                                                                
    console.log(err.message);
  });

  fs.createReadStream(csvfile).pipe(parser);    //open file as a stream and pipe it to the parser                                                             
};

关于javascript - 为什么我在运行此示例 node.js 代码时得到 "TypeError: object is not a function"？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25603947/