Write objects into file with Node js

Question

I ve searched all over stackoverflow   google for this  but can t seem to figure it out    I m scraping social media links of a given URL page  and the function returns an object with a list of URLs    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   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   n   forEach function  line       console log line        var obj   request line  gotHTML        console log obj        fs writeFileSync    data json   obj    utf-8              for reference -- the gotHTML function    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 lt socialurls length  i                     if socialurls i  test href   amp  amp  social ids indexOf href   lt  0                         social ids push href                                                               return social ids

User · Answer

If you re geting  object object  then use JSON stringify  fs writeFile    data json   JSON stringify obj     utf-8     It worked for me

User · Answer

Building on what deb2fast said I would also pass in a couple of extra parameters to JSON stringify   to get it to pretty format   fs writeFileSync    data json   JSON stringify obj  null  2     utf-8      The second param is an optional replacer function which you don t need in this case so null works   The third param is the number of spaces to use for indentation  2 and 4 seem to be popular choices

User · Answer

In my experience JSON stringify is slightly faster than util inspect  I had to save the result object of a DB2 query as a json file  The query returned an object of 92k rows  the conversion took very long to complete with util inspect  so I did the following test by writing the same 1000 record object to a file with both methods    JSON Stringify  fs writeFile    data json   JSON stringify obj  null  2       Time  3 57  3 min 57 sec   Result s format              PROB    00001        BO    AXZ        CNTRY    649                   util inspect  var util   require  util    fs writeFile    data json   util inspect obj  false  2  false       Time  4 12  4 min 12 sec   Result s format       PROB   00001       BO   AXZ       CNTRY   649

User · Answer

obj is an array in your example     fs writeFileSync filename  data   options   requires either String or Buffer in the data parameter  see docs   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       Or      writes   https   twitter com    101Cookbooks    http   www facebook com 101cookbooks   var util   require  util    fs writeFileSync    data json   util inspect obj     utf-8      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

User · Answer

could you try doing JSON stringify obj    Like this   var stringify   JSON stringify obj   fs writeFileSync    data json   stringify    utf-8

User · Answer

Just incase anyone else stumbles across this  I use the fs-extra library in node and write javascript objects to a file like this   const fse   require  fs-extra    fse outputJsonSync  path to output file json   objectToWriteToFile

[javascript] Write objects into file with Node.js

Examples related to javascript

Examples related to node.js

Examples related to file-io