Uncaught TypeError Cannot read property length of undefined

Question

How do I avoid the following error when trying to take data from an AJAX call and plug it into another function when I click the submit button   The console log call in the ajax function shows that the data is grabbed and I d hoped then stored in json data   The aim was then to use this data to alter a string submitted through an HTML form   The error is then returned at the line in the  click  function   console log json data length          lt title gt Test Form lt  title gt    lt script type  text javascript  src  https   ajax googleapis com ajax libs jquery 1 7 jquery min js  gt  lt  script gt   lt style gt       results box           border  red 5px solid                          place           border   cccccc 1px solid                     lt  style gt   lt script type  text javascript  gt    document  ready function         var json source    https   spreadsheets google com feeds list 0ApL1zT2P00q5dG1wOUMzSlNVV3VRV2pwQ2Fnbmt3M0E od7 public basic alt json       var string data          var json data     ajax           dataType   jsonp           url  json source          success  function data               var data obj                   for  i 0  i lt data feed entry length  i                     var el     key   data feed entry i  title   t     value     lt p gt  lt a href    data feed entry i  content   t     gt   data feed entry i  title   t     lt  a gt  lt  p gt                     data obj push el                 console log  data grabbed                     return data obj                             error  function jqXHR  textStatus  errorThrown                                results box   html   lt h2 gt Something went wrong  lt  h2 gt  lt p gt  lt b gt     textStatus      lt  b gt      errorThrown      lt  p gt                                 submit   click function event  json data           event preventDefault            console log json data length              function         if      place   val                      var copy string       place   val                var converted string   copy string              for  i 0  i lt json data length  i                       console log data feed entry i  title   t                     converted string   converted string replace json data feed entry i  title   t                           lt a href    json data feed entry i  content   t     gt   json data feed entry i  title   t     lt  a gt                                     results box   text converted string  html                            document ready end    lt  script gt   lt  head gt    lt body gt       lt div id  wrapper  gt       lt div id  query box  class  panel  gt             lt form id  form submit  gt  lt h4 gt Copy to process  lt  h4 gt             lt textarea id  place  gt  lt  textarea gt             lt input type  submit  value  Go    gt            lt  form gt       lt  div gt      lt div id  results box   gt Results will appear here lt  div gt     lt  div gt

User · Answer

console log typeof json data      undefined        json data length    There is no spoon          or more simply     console log json data   json data length    json data is null or undefined

User · Answer

You are accessing an object that is not defined    The solution is check for null or undefined  to see whether the object exists  and only then iterate

User · Answer

ProjectID  JSON data format problem Remove  ProjectID    This value   collection objeckt key value              ProjectID                       name    ProjectID                value    16 36 8 7                group    Genel                editor                      type    combobox                    options                          url        jsonEntityVarServices   id 6 amp task 7                        valueField    value                        textField    text                        multiple    true                                                id    14                entityVarID    16                EVarMemID    47

User · Answer

You are not passing the variable correctly  One fast solution is to make a global variable like this   var global json data    document  ready function         var json source    https   spreadsheets google com feeds list 0ApL1zT2P00q5dG1wOUMzSlNVV3VRV2pwQ2Fnbmt3M0E od7 public basic alt json       var string data          var json data     ajax           dataType   json      Return JSON         url  json source          success  function data               var data obj                   for  i 0  i lt data feed entry length  i                     var el     key   data feed entry i  title   t     value     lt p gt  lt a href    data feed entry i  content   t     gt   data feed entry i  title   t     lt  a gt  lt  p gt                     data obj push el                 console log  data grabbed                  global json data     data obj               return data obj                              error  function jqXHR  textStatus  errorThrown                                results box   html   lt h2 gt Something went wrong  lt  h2 gt  lt p gt  lt b gt     textStatus      lt  b gt      errorThrown      lt  p gt                                 submit   click function event           var json data   global json data          event preventDefault            console log json data length              function         if      place   val                      var copy string       place   val                var converted string   copy string              for  i 0  i lt json data length  i                       console log data feed entry i  title   t                     converted string   converted string replace json data feed entry i  title   t                           lt a href    json data feed entry i  content   t     gt   json data feed entry i  title   t     lt  a gt                                     results box   text converted string  html                            document ready end

[javascript] Uncaught TypeError: Cannot read property 'length' of undefined

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