Check if a key exists inside a json object

Question

amt   10 00  email   sam gmail com  merchant id   sam  mobileNo   9874563210  orderID   123456  passkey   1234    The above is the JSON object I m dealing with  I want to check if the  merchant id  key exists  I tried the below code  but it s not working  Any way to achieve it    lt script gt  window onload   function getApp       var thisSession   JSON parse   lt  php echo json encode   POST     gt         console log thisSession     if     merchant id  in thisSession   0             do nothing        else          alert  yeah           lt  script gt

User · Answer

you can do like this   if  merchant id  in thisSession       will return true if exist     console log  Exist         or   if thisSession  merchant id         will return its value if exist     console log  Exist

User · Answer

I change your if statement slightly and works  also for inherited obj - look on snippet   if    merchant id  in thisSession   alert  yeah       x000D   x000D  var sessionA     x000D    amt   10 00   x000D    email   sam gmail com   x000D    merchant id   sam   x000D    mobileNo   9874563210   x000D    orderID   123456   x000D    passkey   1234   x000D    x000D   x000D  var sessionB     x000D    amt   10 00   x000D    email   sam gmail com   x000D    mobileNo   9874563210   x000D    orderID   123456   x000D    passkey   1234   x000D    x000D   x000D   x000D  var sessionCfromA   Object create sessionA      inheritance x000D  sessionCfromA name    john   x000D   x000D   x000D  if     merchant id  in sessionA   alert  merchant id not in sessionA    x000D  if     merchant id  in sessionB   alert  merchant id not in sessionB    x000D  if     merchant id  in sessionCfromA   alert  merchant id not in sessionCfromA    x000D   x000D  if   merchant id  in sessionA  alert  merchant id in sessionA    x000D  if   merchant id  in sessionB  alert  merchant id in sessionB    x000D  if   merchant id  in sessionCfromA  alert  merchant id in sessionCfromA    x000D   x000D   x000D

User · Answer

This code causes esLint issue  no-prototype-builtins foo hasOwnProperty  quot bar quot     The suggest way here is  Object prototype hasOwnProperty call foo   quot bar quot

User · Answer

Type check also works    if typeof Obj property     undefined           Assign value to the property here     Obj property   someValue

User · Answer

function to check undefined and null objects function elementCheck objarray  callback            var list undefined    quot  quot           async forEachOf objarray  function  item  key  next key                console log  quot item----- gt  quot   item               console log  quot key----- gt  quot   key               if  item    undefined    item                          list undefined   list undefined    quot  quot    key    quot      quot                   next key null                 else                   next key null                            function  next key                callback list undefined                     here is an easy way to check whether object sent is contain undefined or null var objarray    quot passenger id quot   quot 59b64a2ad328b62e41f9050d quot    quot started ride quot   quot 1 quot    quot bus id quot   quot 59b8f920e6f7b87b855393ca quot    quot route id quot   quot 59b1333c36a6c342e132f5d5 quot    quot start location quot   quot  quot    quot stop location quot   quot  quot    elementCheck objarray function list   console log  quot list quot

User · Answer

There s several ways to do it  depending on your intent     thisSession hasOwnProperty  merchant id    will tell you if thisSession has that key itself  i e  not something it inherits from elsewhere    merchant id  in thisSession  will tell you if thisSession has the key at all  regardless of where it got it   thisSession  merchant id   will return false if the key does not exist  or if its value evaluates to false for any reason  e g  if it s a literal false or the integer 0 and so on

User · Answer

Try this   if thisSession hasOwnProperty  merchant id          the JS Object thisSession should be like     amt   10 00   email   sam gmail com   merchant id   sam   mobileNo   9874563210   orderID   123456   passkey   1234      you can  find the details here

User · Answer

I wanted to point this out even though I m late to the party  The original question you were trying to find a  Not IN  essentially  It looks like is not supported from the research  2 links below  that I was doing      So if you wanted to do a  Not In       merchant id  in x  true   merchant id NotInObject  in x  false    I d recommend  just setting that expression    to what you re looking for  if    merchant id  in thisSession   false           do nothing    else        alert  yeah        https   developer mozilla org en-US docs Web JavaScript Reference Operators in http   www w3schools com jsref jsref operators asp

User · Answer

You can try if typeof object      undefined

[javascript] Check if a key exists inside a json object

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