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> (en-US), <audio> (en-US), <video> (en-US), <style> (en-US) or <link> (en-US)).

建構式

ProgressEvent() (en-US)

Creates a ProgressEvent event with the given parameters.

屬性

Also inherits properties from its parent Event.

ProgressEvent.lengthComputable (en-US) Read only

Is a Boolean (en-US) 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 (en-US) 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 (en-US) 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.

方法

Also inherits methods from its parent Event.

ProgressEvent.initProgressEvent() (en-US) 已棄用 非標準

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

範例

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()

規格

Specification
XMLHttpRequest Standard
# interface-progressevent

瀏覽器相容性

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參見

  • The Event base interface.