Cannot read property 'value' of undefined" on dojo/request/iframe post

Question

I have an image upload function that uploads form with image like this:

iframe(url, {
    form: dom.byId("myform"),
    handleAs: "json",
    timeout: 5000,
    method: "POST"
}).then(function () {
    console.log("Success");
}, function (Err) {
    console.log(Err);
});

On server side I get the image, but on client side I get TypeError: Cannot read property 'value' of undefined↵ at I [as handleResponse] (http://ajax.googleapis.com/ajax/libs/dojo/1.9.2/dojo/request/iframe.js:9:114)↵ at r (http://ajax.googleapis.com/ajax/libs/dojo/1.9.2/dojo/dojo.js:206:81)". I have no returned value! I do not get what causing the error! Please help!

Your links are broken. Where does this error occur in your code? Pointing them to iframe.js isn't very helpful... — Bucket
I get value of Err = "Cannot read property 'value' of undefined↵ at I [as handleResponse] (ajax.googleapis.com/ajax/libs/dojo/1.9.2/dojo/request/…)↵ at r (ajax.googleapis.com/ajax/libs/dojo/1.9.2/dojo/dojo.js:206:81) "! It's not my fault that the links are broken! It's the value of the error! — levkaster
In the future, please post your relevant server code as well, especially since you tagged this post with asp.net-mvc-4. It took a lot longer to find the cause of your issue because I couldn't tell what you were returning as a response. — Bucket

Bucket Bucket · Accepted Answer · 2014-04-07T21:38:05

From the Dojo Reference Guide:

Important: If your payload is something other than html or xml (e.g. text, JSON) the server response needs to enclose the content in a <textarea> tag. This is because this is the only cross-browser way for this provider to know when the content has been successfully loaded. Therefore the server response should look something like this:

<html>
  <body>
    <textarea>
      payload
    </textarea>
  </body>
</html>

All you should need to do to fix this issue is to wrap your JSON response in a <textarea> tag. The reason for this is in iframe.js, starting at line 300:

if(handleAs === 'xml'){
    ...
}else{
    // 'json' and 'javascript' and 'text'
    response.text = doc.getElementsByTagName('textarea')[0].value; // text
}

So here is where you get your error that reads, "Cannot read property 'value' of undefined." Dojo can't find a <textarea> element in your response, so doc.getElementsByTagName('textarea') returns an empty array. The 0th element of an empty array, [], is undefined, and dereferencing it will throw this error.

Cannot read property 'value' of undefined" on dojo/request/iframe post

1 Answers