Cannot read property 'value' of undefined"

2019-08-08 08:22发布

站内问答 / JavaScript
492 1 5

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!

1条回答
不美不萌又怎样
2楼-- · 2019-08-08 09:14

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.

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