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Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
Summary
This property specifies a callback function to be run repeatedly while the operation represented by a FileRequest object is in progress.
Syntax
instanceOfFileRequest.onprogress = function;
Where instanceOfFileRequest is a FileRequest object and function is the JavaScript function to execute.
Each time the function callback is called, it gets an object as its first parameter. Those objects contain two properties:
loaded- A number representing the current amount of bytes processed by the operation.
total- A number representing the total amount of bytes that will be processed by the operation.
Example
// Assuming 'request' which is a FileRequest object
request.onprogress = function (status) {
var progress = document.querySelector('progress');
progress.value = status.loaded;
progress.max = status.total;
}
Specification
Not part of any current specification.