var i returns undefined?

Question

I want to retrieve my database values and insert them into a table.

I am trying to iterate i onto an array.

However, it returns undefined and there is no output. Why is this so?

Could it be an issue with the script or the body tag?

Script

function getitemdetails() {
  var xmlhttp = new XMLHttpRequest();
  var url = serverURL() + "/mycasefeed.php";
  url += "?Case_ID=" + decodeURIComponent(getUrlVars()["Case_ID"]);
  xmlhttp.onreadystatechange = function() {
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
      getitemResult(xmlhttp.responseText);
    };
  }
  xmlhttp.open("GET", url, true);
  xmlhttp.send();
}

function getitemResult(response) {
  var arr = JSON.parse(response);
  var i;


    for(i = 0; i < arr.length; i++) {

    $("#mycase").append("<tr><td>" + arr[i].CaseDes +
    arr[i].Case_Pic +
    "<br>" + arr[i].categoryname +
    "<br>" + arr[i].Caselat +
    "<br>" + arr[i].Caselong +
    "<br>" + arr[i].CaseTime +
    "<br>" + arr[i].details + "</td></tr>");
}
$("#mycaseresult").table("refresh");
}

getitemdetails();

Body

<div id="SearchResult" class="ui-content">
  <table data-role="table" data-mode="reflow" class="ui-responsive" id="mycaseresult">
    <thead>
      <tr>
        *insert values here*
      </tr>
    </thead>
    <tbody id="mycase">

    </tbody>
  </table>
</div>

Here's your code `var i; alert(i);`. Why do you expect `i` to have a value? — Mike Cluck, Dec 06 '16 at 15:59
you dont instantiate i you just initialise it and then do nothing with it? — Dennington-bear, Dec 06 '16 at 15:59
`var i; alert(i);` - You have just declared `i`, it has no value so you see `undefined` — Alex K., Dec 06 '16 at 15:59
Solution to your question - [definition of undefined in JavaScript](http://www.w3schools.com/jsref/jsref_undefined.asp) — Nikhil Nanjappa, Dec 06 '16 at 16:01
Also look at [JavaScript for loop](http://stackoverflow.com/questions/10585745/javascript-for-loop-work-hows) or [jQuery each](http://stackoverflow.com/questions/6364031/jquery-each-objects) — thekodester, Dec 06 '16 at 16:04

score 1 · Answer 1 · answered Dec 06 '16 at 16:01

1

the reason it is returned undefined is because the variable has no content.

answered Dec 06 '16 at 16:01

ca1c

1,111
10
23

score 1 · Answer 2 · answered Dec 06 '16 at 16:01

In javascript, any empty variable (declared, but not defined) is undefined.

var a;
var b = {};

function foo(parameter) {
    console.log(parameter);
}

console.log(a); // Outputs: `undefined`
console.log(b.cool); // Outputs: `undefined`
foo(); // Outputs: `undefined`

On your code, looks like you are trying to iterate on an array, but you don't have any iteration loop.

Try:

function getitemResult(response) {
  var arr = JSON.parse(response);
  for(var i=0; i < arr.length; i++) {
      $("#mycase").append("<tr><td>" + arr[i].CaseDes +
          arr[i].Case_Pic +
          "<br>" + arr[i].categoryname +
          "<br>" + arr[i].Caselat +
          "<br>" + arr[i].Caselong +
          "<br>" + arr[i].CaseTime +
          "<br>" + arr[i].details + "</td></tr>");
   }
}

i tried to insert your code but I still do not get an output — Zesty, Dec 07 '16 at 01:06

var i returns undefined?

2 Answers2