Deserializing a JSON into a JavaScript object

Question

I have a string in a Java server application that is accessed using AJAX  It looks something like the following   var json           adjacencies                          nodeTo    graphnode2              nodeFrom    graphnode1              data                   color     557EAA                                    data             color     EBB056           type    triangle           dim   9             id    graphnode1        name    graphnode1           adjacencies            data             color     EBB056           type    triangle           dim   9             id    graphnode2        name    graphnode2        When the string gets pulled from the server  is there an easy way to turn this into a living JavaScript object  or array   Or do I have to manually split the string and build my object manually

User · Answer

Do like jQuery does   the essence   function parseJSON data        return window JSON  amp  amp  window JSON parse   window JSON parse  data      new Function  return     data            testing obj   parseJSON    name   John      alert obj name     This way you don t need any external library and it still works on old browsers

User · Answer

Modern browsers support JSON parse     var arr from json   JSON parse  json string      In browsers that don t  you can include the json2 library

User · Answer

If you paste the string in server-side into the html don t need to do nothing   For plain java in jsp   var jsonObj  lt   jsonStringInJavaServlet  gt     For jsp width struts   var jsonObj  lt s property value  jsonStringInJavaServlet  escape  false  escapeHtml  false   gt

User · Answer

I think this should help   Also documentations also prove that you can use require   for json files  https   www bennadel com blog 2908-you-can-use-require-to-load-json-javascript-object-notation-files-in-node-js htm  var jsonfile   require    path to jsonfile json    node   jsonfile adjacencies nodeTo  node2   jsonfile adjacencies nodeFrom  node3   jsonfile adjacencies data  color    other things

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TO collect all item  of an array and return a json object  collectData  function  arrayElements             var main                for  var i   0  i  lt  arrayElements length  i                  var data                   this e   arrayElements i                           data text   arrayElements i  text              data val   arrayElements i  value              main i    data                    return main           TO parse the same data we go through like this   dummyParse  function  json                   var o   JSON parse json     conerted the string into JSON object                   each o  function                  inner   this                each inner  function  index                    alert this text

User · Answer

You could also use eval   but JSON parse   is safer and easier way  so why would you   good and works  var yourJsonObject   JSON parse json as text     I don t see any reason why would you prefer to use eval  It only puts your application at risk    That said - this is also possible   bad - but also works  var yourJsonObject   eval json as text     Why is eval a bad idea   Consider the following example   Some third party or user provided JSON string data   var json             adjacencies                          nodeTo   function                return  delete server files - you have been hacked                              nodeFrom    graphnode1              data                   color     557EAA                                    data             color     EBB056           type    triangle           dim   9             id    graphnode1        name    graphnode1           adjacencies            data             color     EBB056           type    triangle           dim   9             id    graphnode2        name    graphnode2          Your server-side script processes that data   Using JSON parse   window onload   function      var placeholder   document getElementById  placeholder1      placeholder innerHTML   JSON parse json  0  adjacencies 0  nodeTo      will throw   Uncaught SyntaxError  Unexpected token u in JSON at position X     Function will not get executed    You are safe   Using eval     window onload   function      var placeholder   document getElementById  placeholder1      placeholder innerHTML   eval json  0  adjacencies 0  nodeTo      will execute the function and return the text    If I replace that harmless function with one that removes files from your website folder you have been hacked  No errors warnings will get thrown in this example   You are NOT safe   I was able to manipulate a JSON text string so it acts as a function which will execute on the server    eval JSON  0  adjacencies 0  nodeTo expects to process a JSON string but  in reality  we just executed a function on our server    This could also be prevented if we server-side check all user-provided data before passing it to an eval   function but why not just use the built-in tool for parsing JSON and avoid all this trouble and danger

User · Answer

And if you also want the deserialised object to have functions  you could use my small tool  https   github com khayll jsmix    first you ll need to define your model var GraphNode   function       GraphNode prototype getType   function        return this  type     var Adjacency   function       Adjacency prototype getData  n function         return this data       then you could say  var result   JSMix jsonData       withObject GraphNode prototype            withObject Adjacency prototype     adjacencies        build       and use them console log result 1  0  getData

User · Answer

The whole point of JSON is that JSON strings can be converted to native objects without doing anything  Check this link  You can use either eval string  or JSON parse string    However  eval is risky  From json org      The eval function is very fast    However  it can compile and execute any JavaScript program    so there can be security issues    The use of eval is indicated when the source is trusted and competent    It is much safer to use a JSON parser    In web applications over XMLHttpRequest    communication is permitted only to the same origin that   provide that page  so it is trusted    But it might not be competent    If the server is not rigorous in its JSON encoding    or if it does not scrupulously validate all of its inputs    then it could deliver invalid JSON text that could be carrying dangerous script    The eval function would execute the script  unleashing its malice

[javascript] Deserializing a JSON into a JavaScript object

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