Proper way to return JSON using node or Express

Question

So  one can attempt to fetch the following JSON object     curl -i -X GET http   echo jsontest com key value anotherKey anotherValue HTTP 1 1 200 OK Access-Control-Allow-Origin    Content-Type  application json  charset ISO-8859-1 Date  Wed  30 Oct 2013 22 19 10 GMT Server  Google Frontend Cache-Control  private Alternate-Protocol  80 quic 80 quic Transfer-Encoding  chunked        anotherKey    anotherValue       key    value        Is there a way to produce exactly the same body in a response from a server using node or express  Clearly  one can set the headers and indicate that the content-type of the response is going to be  application json   but then there are different ways to write send the object  The one that I have seen commonly being used is by using a command of the form   response write JSON stringify anObject      However  this has two points where one could argue as if they were  problems     We are sending a string  Moreover  there is no new line character in the end    Another idea is to use the command   response send anObject     This appears to be sending a JSON object based on the output of curl similar to the first example above  However  there is no new line character in the end of the body when curl is again being used on a terminal  So  how can one actually write down something like this with a new line character appended in the end using node or node express

User · Answer

The res json   function should be sufficient for most cases   app get       req  res    gt  res json   answer  42        The res json   function converts the parameter you pass to JSON using JSON stringify   and sets the Content-Type header to application json  charset utf-8 so HTTP clients know to automatically parse the response

User · Answer

You can just prettify it using pipe and one of many processor  Your app should always response with as small load as possible     curl -i -X GET http   echo jsontest com key value anotherKey anotherValue   underscore print   https   github com ddopson underscore-cli

User · Answer

You can make a helper for that  Make a helper function so that you can use it everywhere in your application  function getStandardResponse status message data       return           status  status          message   message          data   data            Here is my topic route where I am trying to get all topics   router get      async  req  res    gt        const topics   await Topic find   sort  name        return res json getStandardResponse true      topics          Response we get     status   true   message        data                    description    sqswqswqs            timestamp    2019-11-29T12 46 21 633Z             id    5de1131d8f7be5395080f7b9            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575031579309 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0                       description    sqswqswqs            timestamp    2019-11-29T12 50 35 627Z             id    5de1141bc902041b58377218            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575031835605 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0                       description                 timestamp    2019-11-30T06 51 18 936Z             id    5de211665c3f2c26c00fe64f            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575096678917 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0                       description    null            timestamp    2019-11-30T06 51 41 060Z             id    5de2117d5c3f2c26c00fe650            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575096701051 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0                       description    swqdwqd wwwwdwq            timestamp    2019-11-30T07 05 22 398Z             id    5de214b2964be62d78358f87            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575097522372 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0                       description    swqdwqd wwwwdwq            timestamp    2019-11-30T07 36 48 894Z             id    5de21c1006f2b81790276f6a            name    topics test xqxq            thumbnail    waterfall-or-agile-inforgraphics-thumbnail-1575099408870 jpg            category id    5de0fe0b4f76c22ebce2b70a              v   0

User · Answer

If you re using Express  you can use this  res setHeader  Content-Type    application json    res send JSON stringify  key  quot value quot       or just this res json  key  quot value quot

User · Answer

For the header half of the question  I m gonna give a shout out to res type here   res type  json     is equivalent to  res setHeader  Content-Type    application json     Source  express docs      Sets the Content-Type HTTP header to the MIME type as determined by mime lookup   for the specified type  If type contains the         character  then it sets the Content-Type to type

User · Answer

You can use a middleware to set the default Content-Type  and set Content-Type differently for particular APIs  Here is an example   const express   require  express    const app   express     const port   process env PORT    3000   const server   app listen port    server timeout   1000   60   10     10 minutes     Use middleware to set the default Content-Type app use function  req  res  next        res header  Content-Type    application json        next         app get   api endpoint1    req  res    gt        res send JSON stringify  value  1         app get   api endpoint2    req  res    gt           Set Content-Type differently for this particular API     res set   Content-Type    application xml         res send   lt note gt           lt to gt Tove lt  to gt           lt from gt Jani lt  from gt           lt heading gt Reminder lt  heading gt           lt body gt Don t forget me this weekend  lt  body gt           lt  note gt

User · Answer

Since Express js 3x the response object has a json   method which sets all the headers correctly for you and returns the response in JSON format   Example   res json   foo    bar

User · Answer

That response is a string too  if you want to send the response prettified  for some awkward reason  you could use something like JSON stringify anObject  null  3  It s important that you set the Content-Type header to application json  too  var http   require  http     var app   http createServer function req res       res setHeader  Content-Type    application json        res end JSON stringify   a  1          app listen 3000        gt    quot a quot  1   Prettified  var http   require  http     var app   http createServer function req res       res setHeader  Content-Type    application json        res end JSON stringify   a  1    null  3        app listen 3000        gt         gt       quot a quot   1     gt      I m not exactly sure why you want to terminate it with a newline  but you could just do JSON stringify          n  to achieve that  Express In express you can do this by changing the options instead    json replacer  JSON replacer callback  null by default  json spaces  JSON response spaces for formatting  defaults to 2 in development  0 in production  Not actually recommended to set to 40 app set  json spaces   40    Then you could just respond with some json  res json   a  1      It ll use the  json spaces  configuration to prettify it

User · Answer

Older version of Express use app use express json    or bodyParser json   read more about bodyParser middleware  On latest version of express we could simply use res json    const express   require  express        port   process env port    3000      app   express    app get       req  res    gt  res json  key   value      app listen port       gt  console log  Server start at   port

User · Answer

If you are trying to send a json file you can use streams  var usersFilePath   path join   dirname   users min json     apiRouter get   users   function req  res       var readable   fs createReadStream usersFilePath       readable pipe res

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