Javascript loop through object array

Question

I am trying to loop through the following          messages               msgFrom    13223821242            msgBody    Hi there                    msgFrom    Bill            msgBody    Hello              I want to retrieve msgFrom and msgBody  I ve tried           for  var key in data               var obj   data key              for  var prop in obj                  if obj hasOwnProperty prop                    console log prop           obj prop                                             But the console log prints  Object   Any ideas what im doing wrong

User · Answer

All the answers provided here uses normal function but these days most of our code uses arrow functions in ES6. I hope my answer will help readers on how to use arrow function when we do iteration over array of objects

let data = {
      "messages": [{
           "msgFrom": "13223821242",
           "msgBody": "Hi there"
       }, {
          "msgFrom": "Bill",
          "msgBody": "Hello!"
       }]
 }

Do .forEach on array using arrow function

 data.messages.forEach((obj, i) => {
     console.log("msgFrom", obj.msgFrom);
     console.log("msgBody", obj.msgBody);
 });

Do .map on array using arrow function

 data.messages.map((obj, i) => {
     console.log("msgFrom", obj.msgFrom);
     console.log("msgBody", obj.msgBody);
 });

User · Answer

To loop through an object array or just array in javascript  you can do the following   var cars     name   Audi     name   BMW     name   Ferrari     name   Mercedes     name   Maserati      for var i   0  i  lt  cars length  i          console log cars i  name       There is also the forEach   function  which is more  javascript-ish  and also less code but more complicated for its syntax   cars forEach function  car        console log car name         And both of them are outputting the following      Audi    BMW    Ferrari    Mercedes    Maserati

User · Answer

Iterations   Method 1  forEach method  messages forEach function message       console log message         Method 2  for  of method  for let message of messages      console log message       Note  This method might not work with objects  such as   let obj     a   foo   b    c   bar   d   daz     e   qux        Method 2  for  in method  for let key in messages          console log messages key

User · Answer

You can use forEach method to iterate over array of objects   data messages forEach function message       console log message        Refer  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Array forEach

User · Answer

Here is a generic way to loop through the field objects in an object  person   for  var property in person        console log property  quot   quot  person property       The person obj looks like this  var person       first name  quot johnny quot       last name   quot johnson quot       phone  quot 703-3424-1111 quot

User · Answer

To reference the contents of the single array containing one or more objects i e  everything in the brackets of something like this   messages     a  1  b  2      just add  0  to the query to get the first array element  e g  messages 0  will reference the object   a  1  b  2  as opposed to just messages which would reference the entire array    a  1  b  2    from there you can work with the result as typical object and use Object keys for example to get  a  and  b

User · Answer

It appears you may just have missed the  messages  property in the data  so the loop is likely iterating the root Object rather than the Array   for  var key in data messages        var obj   data messages key                  Unless data was set to messages before the given snippet   Though  you should consider changing that to a normal for loop for the Array   for  var i   0  l   data messages length  i  lt  l  i          var obj   data messages i

User · Answer

In your script  data is your whole object   key is  messages   which is an array you need to iterate through like this       for  var key in data           var arr   data key          for  var i   0  i  lt  arr length  i                  var obj   arr  i               for  var prop in obj                   if obj hasOwnProperty prop                       console log prop           obj prop

User · Answer

for  let key in data        let value   data key       for  i   0  i  lt  value length  i            console log value i  msgFrom         console log value i  msgBody

User · Answer

The suggested for loop is quite fine but you have to check the properties with hasOwnProperty  I d rather suggest using Object keys   that only returns  own properties  of the object  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Object keys    x000D   x000D  var data     x000D       messages      x000D           msgFrom    13223821242   x000D           msgBody    Hi there  x000D           x000D           msgFrom    Bill   x000D           msgBody    Hello   x000D         x000D     x000D   x000D  data messages forEach function message  index    x000D      console log  message index    index   x000D      Object keys message  forEach function prop        x000D          console log prop           message prop    x000D          x000D      x000D   x000D   x000D

[javascript] Javascript loop through object array?

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