Details
-
Improvement
-
Status: Open
-
Minor
-
Resolution: Unresolved
-
None
-
None
-
Android, ios, Browser
Description
When `FileReader` add onEvent listener such as `onload`, it will add the listener to inner `_realReader` , but when it invoke the listener, it use the FileReader as `this`.
1. When add onload listener in application code.
```javascript
var fileReader = new FileReader();
fileReader.onload = function() {};
```
it will call `www/FileReader.js defineEvent`
```javascript
function defineEvent(eventName) {
utils.defineGetterSetter(FileReader.prototype, eventName, function()
, function(value)
{ this._realReader[eventName] = value; });
}
```
the listener is added to `this._realReader`.
And when the listener is triggered for example in `readSuccessCallback`
it will invoke the method with `this`.
```javascript
this.onload(new ProgressEvent("load",
));
```
in the normal senario, it will ok, but when it work with some polyfilles such as `zone.js of angular4`, it will fail because `zone.js` have some special handling which require the `this` object be the same when add listener and invoke listener.
