Proper way to catch exception from JSON parse

Question

I   m using JSON parse on a response that sometimes contains a 404 response  In the cases where it returns 404  is there a way to catch an exception and then execute some other code   data   JSON parse response  function  key  value        var type      if  value  amp  amp  typeof value      object             type   value type          if  typeof type      string   amp  amp  typeof window type       function                 return new window type   value                       return value

User · Answer

We can check error  amp  404 statusCode  and use try    catch  err       You can try this     x000D   x000D  const req   new XMLHttpRequest    x000D  req onreadystatechange   function     x000D      if  req status    404    x000D          console log  404    x000D          return false  x000D        x000D   x000D      if    req readyState    4  amp  amp  req status    200   x000D          return false  x000D   x000D      const json    function raw    x000D          try   x000D              return JSON parse raw   x000D            catch  err    x000D              return false  x000D            x000D         req responseText   x000D   x000D      if   json  x000D          return false  x000D   x000D      document body innerHTML    Your city       json city     lt br gt Your isp       json org  x000D     x000D  req open  GET    https   ipapi co json    true   x000D  req send    x000D   x000D   x000D    Read more     Catch a 404 error for XHR

User · Answer

You can try this   Promise resolve JSON parse response   then json   gt        response   json      catch err   gt        response   response

User · Answer

I am fairly new to Javascript  But this is what I understood  JSON parse   returns SyntaxError exceptions when invalid JSON is provided as its first parameter  So  It would be better to catch that exception as such like as follows   try       let sData                            id    1                name    UbuntuGod                        console log JSON parse sData      catch  objError        if  objError instanceof SyntaxError            console error objError name         else           console error objError message             The reason why I made the words  first parameter  bold is that JSON parse   takes a reviver function as its second parameter

User · Answer

i post something into an iframe then read back the contents of the iframe with json parse   so sometimes it s not a json string   Try this   if response        try           a   JSON parse response         catch e            alert e      error in the above string  in this case  yes

User · Answer

This promise will not resolve if the argument of JSON parse   can not be parsed into a JSON object   Promise resolve JSON parse    key   value      then json   gt        console log json      catch err   gt        console log err

[javascript] Proper way to catch exception from JSON.parse

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