ProgressEvent

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>).

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Constructor

ProgressEvent()

Creates a ProgressEvent event with the given parameters.

Properties

Also inherits properties from its parent Event.

ProgressEvent.lengthComputable Read only

Is 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

Is an unsigned long long representing the amount of work already performed by the underlying process. The ratio of work done can be calculated with the property and ProgressEvent.total. When downloading a resource using HTTP, this only represent the part of the content itself, not headers and other overhead.

ProgressEvent.total Read only

Is an unsigned long long representing the total amount of work that the underlying process is in the progress of performing. When downloading a resource using HTTP, this only represent the content itself, not headers and other overhead.

Methods

Also inherits methods from its parent Event.

ProgressEvent.initProgressEvent()

Initializes a ProgressEvent created using the deprecated Document.createEvent("ProgressEvent") method.

Examples

The following example adds a ProgressEvent to a new XMLHTTPRequest and uses it to display the status of the request.

var progressBar = document.getElementById("p"),
    client = new XMLHttpRequest()
client.open("GET", "magical-unicorns")
client.onprogress = function(pe) {
  if(pe.lengthComputable) {
    progressBar.max = pe.total
    progressBar.value = pe.loaded
  }
}
client.onloadend = function(pe) {
  progressBar.value = pe.loaded
}
client.send()

Specifications

Browser compatibility

See also

• The Event base interface.