The ProgressEvent
interface represents events measuring progress of an underlying process, like an HTTP request (for an XMLHttpRequest
, or the loading of the underlying resource of an <img>
, <audio>
, <video>
, <style>
or <link>
).
The ProgressEvent
interface represents events measuring progress of an underlying process, like an HTTP request (for an XMLHttpRequest
, or the loading of the underlying resource of an <img>
, <audio>
, <video>
, <style>
or <link>
).
ProgressEvent()
Creates a ProgressEvent
event with the given parameters.
Also inherits properties from its parent Event
.
ProgressEvent.lengthComputable
Read only
A boolean flag indicating if the total work to be done, and the amount of work already done, by the underlying process is calculable. In other words, it tells if the progress is measurable or not.
ProgressEvent.loaded
Read only
A 64-bit unsigned integer value indicating the amount of work already performed by the underlying process. The ratio of work done can be calculated by dividing total
by the value of this property. When downloading a resource using HTTP, this only counts the body of the HTTP message, and doesn't include headers and other overhead.
ProgressEvent.total
Read only
A 64-bit unsigned integer representing the total amount of work that the underlying process is in the progress of performing. When downloading a resource using HTTP, this is the Content-Length
(the size of the body of the message), and doesn't include the headers and other overhead.
Inherits methods from its parent, Event
.
The following example adds a ProgressEvent
to a new XMLHTTPRequest
and uses it to display the status of the request.
js
const progressBar = document.getElementById("p"), client = new XMLHttpRequest(); client.open("GET", "magical-unicorns"); client.onprogress = (pe) => { if (pe.lengthComputable) { progressBar.max = pe.total; progressBar.value = pe.loaded; } }; client.onloadend = (pe) => { progressBar.value = pe.loaded; }; client.send();
Specification |
---|
XMLHttpRequest Standard # interface-progressevent |
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
ProgressEvent |
16 | 14 | 18 | No | ≤12.1 | 6 | 4.4 | 18 | 18 | ≤12.1 | 6 | 1.0 |
ProgressEvent |
1 | 12 | 3.5 | 10 | ≤12.1 | 3.1 | ≤37 | 18 | 4 | ≤12.1 | 2 | 1.0 |
lengthComputable |
1 | 12 | 3.5 | 10 | ≤12.1 | 3.1 | 4.4 | 18 | 4 | ≤12.1 | 2 | 1.0 |
loaded |
1 | 12 | 3.5 | 10 | ≤12.1 | 3.1 | ≤37 | 18 | 4 | ≤12.1 | 2 | 1.0 |
total |
1 | 12 | 3.5 | 10 | ≤12.1 | 3.1 | ≤37 | 18 | 4 | ≤12.1 | 2 | 1.0 |
Event
base interface.
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https://developer.mozilla.org/en-US/docs/Web/API/ProgressEvent