What is the JavaScript equivalent of var dump or print r in PHP

Question

I would like to see the structure of object in JavaScript  for debugging   Is there anything similar to var dump in PHP

User · Answer

The var dump equivalent in JavaScript  Simply  there isn t one   But  that doesn t mean you re left helpless  Like some have suggested  use Firebug  or equivalent in other browsers   but unlike what others suggested  don t use console log when you have a  slightly  better tool console dir   console dir object       Prints an interactive listing of all properties of the object  This   looks identical to the view that you would see in the DOM tab

User · Answer

I put this forward to help anyone needing something readily practical for giving you a nice  prettified  indented  picture of a JS Node  None of the other solutions worked for me for a Node   cyclical error  or whatever       This walks you through the tree under the DOM Node  without using recursion  and gives you the depth  tagName  if applicable  and textContent  if applicable    Any other details from the nodes you encounter as you walk the tree under the head node can be added as per your interest      function printRNode  node           make sort of human-readable picture of the node    a bit like PHP print r      if  node     undefined    node     null            throwError   node was     typeof node              let s               NB walkDOM could be made into a utility function which you could         call with one or more callback functions as parameters         function walkDOM  headNode          const stack     headNode          const depthCountDowns     1          while  stack length  gt  0            const node   stack pop            const depth   depthCountDowns length - 1             TODO non-text  non-BR nodes could show more details  attributes  properties  etc           const stringRep   node nodeType     3   TEXT       node nodeValue          tag      node tagName          s         repeat  depth     stringRep     n           const lastIndex   depthCountDowns length - 1          depthCountDowns  lastIndex     depthCountDowns  lastIndex   - 1          if  node childNodes length                depthCountDowns push  node childNodes length                stack push      Array from  node childNodes   reverse                        while  depthCountDowns  depthCountDowns length - 1       0                depthCountDowns splice  -1                                 walkDOM  node        return s

User · Answer

As others have already mentioned  the best way to debug your variables is to use a modern browser s developer console  e g  Chrome Developer Tools  Firefox Firebug  Opera Dragonfly  which now disappeared in the new Chromium-based  Blink  Opera  but as developers say   Dragonfly is not dead though we cannot give you more information yet     But in case you need another approach  there s a really useful site called  php js   http   phpjs org     which provides  JavaScript alternatives to PHP functions  - so you can use them the similar way as you would in PHP  I will copy-paste the appropriate functions to you here  BUT be aware that these codes can get updated on the original site in case some bugs are detected  so I suggest you visiting the phpjs org site   Btw  I m NOT affiliated with the site  but I find it extremely useful    var dump   in JavaScript  Here is the code of the JS-alternative of var dump    http   phpjs org functions var dump  it depends on the echo   function  http   phpjs org functions echo   function var dump           discuss at  http   phpjs org functions var dump       original by  Brett Zamir  http   brett-zamir me       improved by  Zahlii      improved by  Brett Zamir  http   brett-zamir me        depends on  echo             note  For returning a string  use var export   with the second argument set to true             test  skip        example 1  var dump 1          returns 1   int 1      var output           pad char            pad val   4      lgth   0      i   0     var  getFuncName   function fn        var name      W function s    w      s             exec fn       if   name          return   Anonymous              return name 1           var  repeat char   function len  pad char        var str           for  var i   0  i  lt  len  i            str    pad char            return str         var  getInnerVal   function val  thick pad        var ret           if  val     null          ret    NULL         else if  typeof val      boolean           ret    bool     val              else if  typeof val      string           ret    string     val length           val              else if  typeof val      number           if  parseFloat val     parseInt val  10             ret    int     val                else           ret    float     val                             The remaining are not PHP behavior because these values only exist in this exact form in JavaScript     else if  typeof val      undefined           ret    undefined         else if  typeof val      function           var funcLines   val toString            split   n          ret             for  var i   0  fll   funcLines length  i  lt  fll  i              ret     i     0     n    thick pad         funcLines i                 else if  val instanceof Date          ret    Date     val              else if  val instanceof RegExp          ret    RegExp     val              else if  val nodeName             Different than PHP s DOMElement       switch  val nodeType          case 1          if  typeof val namespaceURI      undefined     val namespaceURI      http   www w3 org 1999 xhtml                  Undefined namespace could be plain XML  but namespaceURI not widely supported           ret    HTMLElement      val nodeName                   else             ret    XML Element      val nodeName                           break        case 2          ret    ATTRIBUTE NODE     val nodeName                break        case 3          ret    TEXT NODE     val nodeValue                break        case 4          ret    CDATA SECTION NODE     val nodeValue                break        case 5          ret    ENTITY REFERENCE NODE           break        case 6          ret    ENTITY NODE           break        case 7          ret    PROCESSING INSTRUCTION NODE     val nodeName         val nodeValue                break        case 8          ret    COMMENT NODE     val nodeValue                break        case 9          ret    DOCUMENT NODE           break        case 10          ret    DOCUMENT TYPE NODE           break        case 11          ret    DOCUMENT FRAGMENT NODE           break        case 12          ret    NOTATION NODE           break                    return ret          var  formatArray   function obj  cur depth  pad val  pad char        var someProp           if  cur depth  gt  0          cur depth               var base pad    repeat char pad val    cur depth - 1   pad char       var thick pad    repeat char pad val    cur depth   1   pad char       var str           var val            if  typeof obj      object   amp  amp  obj     null          if  obj constructor  amp  amp   getFuncName obj constructor       PHPJS Resource             return obj var dump                  lgth   0        for  someProp in obj            lgth                  str     array     lgth        n         for  var key in obj            var objVal   obj key           if  typeof objVal      object   amp  amp  objVal     null  amp  amp    objVal instanceof Date   amp  amp    objVal instanceof RegExp   amp  amp                        objVal nodeName              str    thick pad         key        gt  n    thick pad    formatArray objVal  cur depth   1  pad val              pad char             else             val    getInnerVal objVal  thick pad             str    thick pad         key        gt  n    thick pad   val     n                           str    base pad      n         else         str    getInnerVal obj  thick pad             return str          output    formatArray arguments 0   0  pad val  pad char     for  i   1  i  lt  arguments length  i          output      n     formatArray arguments i   0  pad val  pad char          this echo output       print r   in JavaScript  Here is the print r   function  http   phpjs org functions print r  It depends on echo   too   function print r array  return val          discuss at  http   phpjs org functions print r       original by  Michael White  http   getsprink com       improved by  Ben Bryan      improved by  Brett Zamir  http   brett-zamir me       improved by  Kevin van Zonneveld  http   kevin vanzonneveld net          input by  Brett Zamir  http   brett-zamir me        depends on  echo        example 1  print r 1  true          returns 1  1    var output           pad char            pad val   4      d   this window document      getFuncName   function fn          var name      W function s    w      s               exec fn         if   name            return   Anonymous                  return name 1            repeat char   function len  pad char        var str           for  var i   0  i  lt  len  i            str    pad char            return str         formatArray   function obj  cur depth  pad val  pad char        if  cur depth  gt  0          cur depth               var base pad   repeat char pad val   cur depth  pad char       var thick pad   repeat char pad val    cur depth   1   pad char       var str            if  typeof obj      object   amp  amp  obj     null  amp  amp  obj constructor  amp  amp  getFuncName obj constructor             PHPJS Resource           str     Array n    base pad      n         for  var key in obj            if  Object prototype toString call obj key         object Array                str    thick pad         key        gt      formatArray obj key   cur depth   1  pad val  pad char             else             str    thick pad         key        gt      obj key      n                           str    base pad      n         else if  obj     null    obj     undefined          str             else            for our  resource  class       str   obj toString               return str          output   formatArray array  0  pad val  pad char      if  return val     true        if  d body          this echo output         else         try              We re in XUL  so appending as plain text won t work  trigger an error out of XUL         d   XULDocument          this echo   lt pre xmlns  http   www w3 org 1999 xhtml  style  white-space pre   gt     output     lt  pre gt             catch  e               Outputting as plain text may work in some plain XML         this echo output                     return true        return output      var export   in JavaScript  You may also find the var export   alternative useful  which also depends on echo    http   phpjs org functions var export   function var export mixed expression  bool return          discuss at  http   phpjs org functions var export       original by  Philip Peterson      improved by  johnrembo      improved by  Brett Zamir  http   brett-zamir me          input by  Brian Tafoya  http   www premasolutions com           input by  Hans Henrik  http   hanshenrik tk        bugfixed by  Brett Zamir  http   brett-zamir me       bugfixed by  Brett Zamir  http   brett-zamir me        depends on  echo        example 1  var export null          returns 1  null        example 2  var export  0   Kevin   1   van   2   Zonneveld    true          returns 2   array   n  0   gt   Kevin   n  1   gt   van   n  2   gt   Zonneveld  n          example 3  data    Kevin          example 3  var export data  true          returns 3    Kevin      var retstr           iret           value      cnt   0      x           i   0      funcParts              We use the last argument  not part of PHP  to pass in        our indentation level     idtLevel   arguments 2     2      innerIndent           outerIndent           getFuncName   function fn          var name      W function s    w      s               exec fn         if   name            return   Anonymous                  return name 1             makeIndent   function idtLevel        return  new Array idtLevel   1          join                getType   function inp        var i   0        match  types  cons  type   typeof inp      if  type      object   amp  amp   inp  amp  amp  inp constructor   amp  amp        getFuncName inp constructor       PHPJS Resource           return  resource             if  type      function           return  function             if  type      object   amp  amp   inp             Should this be just null        return  null             if  type      object           if   inp constructor            return  object                 cons   inp constructor toString          match   cons match    w              if  match            cons   match 1  toLowerCase                  types     boolean    number    string    array          for  i   0  i  lt  types length  i              if  cons     types i               type   types i             break                              return type         type     getType mixed expression      if  type     null        retstr    NULL       else if  type      array     type      object         outerIndent    makeIndent idtLevel - 2       innerIndent    makeIndent idtLevel       for  i in mixed expression          value   this var export mixed expression i   1  idtLevel   2         value   typeof value      string    value replace   lt  g    amp lt                    replace   gt  g    amp gt     value        x cnt      innerIndent   i       gt                 getType mixed expression i        array                n          value            iret   x join    n        retstr   outerIndent    array   n    iret     n    outerIndent            else if  type      function         funcParts   mixed expression toString               match  function                   s S                 For lambda functions  var export   outputs such as the following           000lambda 1   Since it will probably not be a common use to        expect this  unhelpful  form  we ll use another PHP-exportable        construct  create function    though dollar signs must be on the        variables in JavaScript   if using instead in JavaScript and you        are using the namespaced version  note that create function   will        not be available as a global     retstr    create function       funcParts 1                   funcParts 2  replace new RegExp       g                       else if  type      resource            Resources treated as null for var export     retstr    NULL       else       retstr   typeof mixed expression      string    mixed expression               mixed expression replace         g      1               replace   0 g     0                 if   bool return        this echo retstr       return null         return retstr      echo   in JavaScript  http   phpjs org functions echo   function echo           discuss at  http   phpjs org functions echo       original by  Philip Peterson      improved by  echo is bad      improved by  Nate      improved by  Brett Zamir  http   brett-zamir me       improved by  Brett Zamir  http   brett-zamir me       improved by  Brett Zamir  http   brett-zamir me        revised by  Der Simon  http   innerdom sourceforge net        bugfixed by  Eugene Bulkin  http   doubleaw com        bugfixed by  Brett Zamir  http   brett-zamir me       bugfixed by  Brett Zamir  http   brett-zamir me       bugfixed by  EdorFaus         input by  JB             note  If browsers start to support DOM Level 3 Load and Save  parsing serializing               note  we wouldn t need any such long code  even most of the code below   See             note  link below for a cross-browser implementation in JavaScript  HTML5 might             note  possibly support DOMParser  but that is not presently a standard              note  Although innerHTML is widely used and may become standard as of HTML5  it is also not ideal for             note  use with a temporary holder before appending to the DOM  as is our last resort below               note  since it may not work in an XML context             note  Using innerHTML to directly add to the BODY is very dangerous because it will             note  break all pre-existing references to HTMLElements         example 1  echo   lt div gt  lt p gt abc lt  p gt  lt p gt abc lt  p gt  lt  div gt            returns 1  undefined    var isNode   typeof module      undefined   amp  amp  module exports  amp  amp  typeof global      undefined   amp  amp     toString call      global       object global      if  isNode        var args   Array prototype slice call arguments       return console log args join               var arg         var argc   arguments length    var argv   arguments    var i   0    var holder  win   this window    var d   win document    var ns xhtml    http   www w3 org 1999 xhtml        If we re in a XUL context   var ns xul    http   www mozilla org keymaster gatekeeper there is only xul      var stringToDOM   function str  parent  ns  container        var extraNSs           if  ns     ns xul          extraNSs     xmlns html      ns xhtml                  var stringContainer     lt     container     xmlns      ns         extraNSs     gt     str     lt      container     gt        var dils   win DOMImplementationLS      var dp   win DOMParser      var ax   win ActiveXObject      if  dils  amp  amp  dils createLSInput  amp  amp  dils createLSParser             Follows the DOM 3 Load and Save standard  but not          implemented in browsers at present  HTML5 is to standardize on innerHTML  but not for XML  though          possibly will also standardize with DOMParser   in the meantime  to ensure fullest browser support  could          attach http   svn2 assembla com svn brettz9 DOMToString DOM3 js  see http   svn2 assembla com svn brettz9 DOMToString DOM3 xhtml for a simple test file        var lsInput   dils createLSInput             If we re in XHTML  we ll try to allow the XHTML namespace to be available by default       lsInput stringData   stringContainer           synchronous  no schema type       var lsParser   dils createLSParser 1  null         return lsParser parse lsInput           firstChild        else if  dp             If we re in XHTML  we ll try to allow the XHTML namespace to be available by default       try           var fc   new dp              parseFromString stringContainer   text xml            if  fc  amp  amp  fc documentElement  amp  amp  fc documentElement localName      parsererror   amp  amp  fc documentElement namespaceURI                http   www mozilla org newlayout xml parsererror xml               return fc documentElement firstChild                       If there s a parsing error  we just continue on         catch  e               If there s a parsing error  we just continue on               else if  ax             We don t bother with a holder in Explorer as it doesn t support namespaces       var axo   new ax  MSXML2 DOMDocument          axo loadXML str         return axo documentElement              else if  win XMLHttpRequest            Supposed to work in older Safari       var req   new win XMLHttpRequest        req open  GET    data application xml charset utf-8   encodeURIComponent str   false         if  req overrideMimeType            req overrideMimeType  application xml                  req send null         return req responseXML                 Document fragment did not work with innerHTML  so we create a temporary element holder        If we re in XHTML  we ll try to allow the XHTML namespace to be available by default       if  d createElementNS  amp  amp   d contentType  amp  amp  d contentType      text html             Don t create namespaced elements if we re being served as HTML  currently only Mozilla supports this detection in true XHTML-supporting browsers  but Safari and Opera should work with the above DOMParser anyways  and IE doesn t support createElementNS anyways      if  d createElementNS  amp  amp     Browser supports the method        d documentElement namespaceURI       We can use if the document is using a namespace         d documentElement nodeName toLowerCase        html        We know it s not HTML4 or less  if the tag is not HTML  even if the root namespace is null           d contentType  amp  amp  d contentType      text html      We know it s not regular HTML4 or less if this is Mozilla  only browser supporting the attribute  and the content type is something other than text html  other HTML5 roots  like svg  still have a namespace                     Don t create namespaced elements if we re being served as HTML  currently only Mozilla supports this detection in true XHTML-supporting browsers  but Safari and Opera should work with the above DOMParser anyways  and IE doesn t support createElementNS anyways   last test is for the sake of being in a pure XML document       holder   d createElementNS ns  container         else            Document fragment did not work with innerHTML       holder   d createElement container             holder innerHTML   str      while  holder firstChild          parent appendChild holder firstChild             return false         throw  Your browser does not support DOM parsing as required by echo             var ieFix   function node        if  node nodeType     1          var newNode   d createElement node nodeName         var i  len        if  node attributes  amp  amp  node attributes length  gt  0            for  i   0  len   node attributes length  i  lt  len  i                newNode setAttribute node attributes i  nodeName  node getAttribute node attributes i  nodeName                            if  node childNodes  amp  amp  node childNodes length  gt  0            for  i   0  len   node childNodes length  i  lt  len  i                newNode appendChild ieFix node childNodes i                             return newNode        else         return d createTextNode node nodeValue                 var replacer   function s  m1  m2           We assume for now that embedded variables do not have dollar sign  to add a dollar sign  you currently must use    var   We might change this  however          Doesn t cover all cases yet  see http   php net manual en language types string php language types string syntax double     if  m1                   return m1   eval m2         else         return s                this php js   this php js          var phpjs   this php js    var ini   phpjs ini    var obs   phpjs obs    for  i   0  i  lt  argc  i          arg   argv i       if  ini  amp  amp  ini  phpjs echo embedded vars            arg   arg replace             w      w   g  replacer              if   phpjs flushing  amp  amp  obs  amp  amp  obs length             If flushing we output  but otherwise presence of a buffer means caching output       obs obs length - 1  buffer    arg        continue             if  d appendChild          if  d body            if  win navigator appName      Microsoft Internet Explorer                  We unfortunately cannot use feature detection  since this is an IE bug with cloneNode nodes being appended           d body appendChild stringToDOM ieFix arg               else             var unappendedLeft   stringToDOM arg  d body  ns xhtml   div                cloneNode true      We will not actually append the div tag  just using for providing XHTML namespace by default            if  unappendedLeft                d body appendChild unappendedLeft                                 else              We will not actually append the description tag  just using for providing XUL namespace by default          d documentElement appendChild stringToDOM arg  d documentElement  ns xul   description                   else if  d write          d write arg         else         console log arg

User · Answer

A nice simple solution for parsing a JSON Response to HTML   var json response   jQuery parseJSON data   html response     JSON Response  lt br   gt     jQuery each json response  function k  v        html response    outputJSONReponse k  v        function outputJSONReponse k  v        var html response   k              if jQuery isArray v     jQuery isPlainObject v             jQuery each v  function j  w                html response    outputJSONReponse j  w                     else           html response    v     lt br   gt               return html response

User · Answer

Firebug   Then  in your javascript   var blah    something   hi   another   noway    console debug  Here is blah   o   blah     Now you can look at the console  click on the statement and see what is inside blah

User · Answer

Most common way   console log object     However I must mention JSON stringify which is useful to dump variables in non-browser scripts   console log  JSON stringify object       The JSON stringify function also supports built-in prettification as pointed out by Simon Zyx   Example   var obj    x  1  y  2  z  3    console log  JSON stringify obj  null  2        spacing level   2   The above snippet will print        x   1     y   2     z   3     On caniuse com you can view the browsers that support natively the JSON stringify function  http   caniuse com json  You can also use the Douglas Crockford library to add JSON stringify support on old browsers  https   github com douglascrockford JSON-js  Docs for JSON stringify  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects JSON stringify  I hope this helps  -

User · Answer

Most modern browsers have a console in their developer tools  useful for this sort of debugging   console log myvar     Then you will get a nicely mapped out interface of the object whatever in the console   Check out the console documentation for more details

User · Answer

You could also try this function  Can t remember the original author  but all credits goes to him her    Works like a charm - 100  the same as var dump in PHP   Check it out    x000D   x000D  function dump arr level    x000D   var dumped text       x000D   if  level  level   0  x000D   x000D     The padding given at the beginning of the line  x000D   var level padding       x000D   for var j 0 j lt level 1 j    level padding            x000D   x000D   if typeof arr      object       Array Hashes Objects x000D    for var item in arr    x000D     var value   arr item   x000D   x000D     if typeof value      object       If it is an array  x000D      dumped text    level padding         item          n   x000D      dumped text    dump value level 1   x000D       else   x000D      dumped text    level padding         item        gt        value       n   x000D       x000D      x000D     else     Stings Chars Numbers etc  x000D    dumped text        gt   arr   lt       typeof arr       x000D     x000D   return dumped text  x000D    x000D   x000D   x000D     Example  x000D   x000D  var employees     x000D        id   1   sex   m   city   Paris      x000D        id   2   sex   f   city   London     x000D        id   3   sex   f   city   New York     x000D        id   4   sex   m   city   Moscow     x000D        id   5   sex   m   city   Berlin    x000D    x000D   x000D   x000D     Open dev console  F12  to see results  x000D   x000D  console log dump employees    x000D   x000D   x000D

User · Answer

I wrote this JS function dump   to work like PHP s var dump     To show the contents of the variable in an alert window  dump variable  To show the contents of the variable in the web page  dump variable   body   To just get a string of the variable  dump variable   none       repeatString   returns a string which has been repeated a set number of times    function repeatString str  num        out           for  var i   0  i  lt  num  i              out    str            return out        dump   displays the contents of a variable like var dump   does in PHP  dump   is better than typeof  because it can distinguish between array  null and object  Parameters      v               The variable     howDisplay       none    body    alert   default      recursionLevel  Number of times the function has recursed when entering nested                     objects or arrays  Each level of recursion adds extra space to the                     output to indicate level  Set to 0 by default  Return Value      A string of the variable s contents Limitations      Can t pass an undefined variable to dump         dump   can t distinguish between int and float      dump   can t tell the original variable type of a member variable of an object      These limitations can t be fixed because these are  features  of JS  However  dump      function dump v  howDisplay  recursionLevel        howDisplay    typeof howDisplay      undefined      alert    howDisplay      recursionLevel    typeof recursionLevel      number     0   recursionLevel       var vType   typeof v      var out   vType       switch  vType            case  number              there is absolutely no way in JS to distinguish 2 from 2 0            so  number  is the best that you can do  The following doesn t work             var er      0-9                 if   isNaN v   amp  amp  v   1     0  amp  amp  er test 3 0                    out    int                                   break      case  boolean           out           v          break      case  string           out          v length            v                break      case  object             check if null         if  v     null                out    null                       If using jQuery  if    isArray v             If using IE  if  isArray v             this should work for all browsers according to the ECMAScript standard          else if  Object prototype toString call v        object Array                  out    array     v length         n               for  var i   0  i  lt  v length  i                      out    repeatString        recursionLevel             i                                dump v i    none   recursionLevel   1      n                             out    repeatString        recursionLevel                           else                 if object             let sContents      n               let cnt   0              for  var member in v                      No way to know the original data type of member  since JS                   always converts it to a string and no other way to parse objects                  sContents    repeatString        recursionLevel            member                               dump v member    none   recursionLevel   1      n                   cnt                              sContents    repeatString        recursionLevel                     out          cnt           sContents                    break      default          out   v          break             if  howDisplay     body             var pre   document createElement  pre            pre innerHTML   out          document body appendChild pre             else if  howDisplay     alert             alert out              return out

[javascript] What is the JavaScript equivalent of var_dump or print_r in PHP?

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