使用 Node.js 将对象写入文件 [英] Write objects into file with Node.js

问题描述

我已经在 stackoverflow/google 上到处搜索了这个，但似乎无法弄清楚.

I've searched all over stackoverflow / google for this, but can't seem to figure it out.

我正在抓取给定 URL 页面的社交媒体链接，该函数返回一个包含 URL 列表的对象.

I'm scraping social media links of a given URL page, and the function returns an object with a list of URLs.

当我尝试将此数据写入不同的文件时，它以 [object Object] 而不是预期的形式输出到文件中:[ 'https://twitter.com/#!/101Cookbooks','http://www.facebook.com/101cookbooks']就像我 console.log() 结果一样.

When I try to write this data into a different file, it outputs to the file as [object Object] instead of the expected: [ 'https://twitter.com/#!/101Cookbooks', 'http://www.facebook.com/101cookbooks'] as it does when I console.log() the results.

这是我在 Node 中读写文件的可悲尝试，尝试读取每一行(url)并通过函数调用输入request(line, gotHTML):

This is my sad attempt to read and write a file in Node, trying to read each line(the url) and input through a function call request(line, gotHTML):

fs.readFileSync('./urls.txt').toString().split('
').forEach(function (line){
    console.log(line); 
    var obj = request(line, gotHTML); 
    console.log(obj); 
    fs.writeFileSync('./data.json', obj , 'utf-8'); 
});   

供参考——gotHTML 函数:

function gotHTML(err, resp, html){ 
    var social_ids = []; 

    if(err){
        return console.log(err); 
    } else if (resp.statusCode === 200){ 
        var parsedHTML = $.load(html); 

        parsedHTML('a').map(function(i, link){
            var href = $(link).attr('href');
            for(var i=0; i<socialurls.length; i++){
                if(socialurls[i].test(href) && social_ids.indexOf(href) < 0 ) {
                    social_ids.push(href); 
                }; 
            }; 
        })
    };

    return social_ids;
};

推荐答案

obj 在您的示例中是一个数组.

obj is an array in your example.

fs.writeFileSync(filename, data, [options]) 需要数据参数中的 String 或 Buffer.查看文档.

fs.writeFileSync(filename, data, [options]) requires either String or Buffer in the data parameter. see docs.

尝试将数组写成字符串格式:

Try to write the array in a string format:

// writes 'https://twitter.com/#!/101Cookbooks', 'http://www.facebook.com/101cookbooks'
fs.writeFileSync('./data.json', obj.join(',') , 'utf-8'); 

或者:

// writes ['https://twitter.com/#!/101Cookbooks', 'http://www.facebook.com/101cookbooks']
var util = require('util');
fs.writeFileSync('./data.json', util.inspect(obj) , 'utf-8');

edit:您在示例中看到数组的原因是节点对 console.log 的实现不只是调用 toString，它还调用 util.格式 查看console.js源码

edit: The reason you see the array in your example is because node's implementation of console.log doesn't just call toString, it calls util.format see console.js source

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