FileReader onload with result and parameter
You should use closure at 'onload' handler. Example: http://jsfiddle.net/2bjt7Lon/
reader.onload = (function (file) { // here we save variable 'file' in closure
return function (e) { // return handler function for 'onload' event
var data = this.result; // do some thing with data
}
})(file);
Try wrapping your onload function in another function. Here the closure gives you access to each file being processed in turn via the variable f
:
function openFiles(evt){
var files = evt.target.files;
for (var i = 0, len = files.length; i < len; i++) {
var file = files[i];
var reader = new FileReader();
reader.onload = (function(f) {
return function(e) {
// Here you can use `e.target.result` or `this.result`
// and `f.name`.
};
})(file);
reader.readAsText(file);
}
}
For a discussion of why a closure is required here see these related questions:
- JavaScript closure inside loops – simple practical example
- Javascript infamous Loop issue?