PerformanceNavigationTiming.unloadEventStart

The unloadEventStart read-only property returns a timestamp representing the time value equal to the time immediately before the user agent starts the unload event of the previous document. If there is no previous document, this property returns 0.

Value

A timestamp representing the time value equal to the time immediately before the user agent starts the unload event of the previous document.

Examples

The following example illustrates this property's usage.

function printNavTimingData() {
  // Use getEntriesByType() to just get the "navigation" events
  performance.getEntriesByType("navigation")
    .forEach((p, i) => {
      console.log(`= Navigation entry[${i}]`);

      // DOM Properties
      console.log(`DOM content loaded = ${p.domContentLoadedEventEnd - p.domContentLoadedEventStart}`);
      console.log(`DOM complete = ${p.domComplete}`);
      console.log(`DOM interactive = ${p.domInteractive}`);

      // Document load and unload time
      console.log(`document load = ${p.loadEventEnd - p.loadEventStart}`);
      console.log(`document unload = ${p.unloadEventEnd - p.unloadEventStart}`);

      // Other properties
      console.log(`type = ${p.type}`);
      console.log(`redirectCount = ${p.redirectCount}`);
    });
}

Specifications

Specification
Navigation Timing Level 2
# dom-performancenavigationtiming-unloadeventstart

Browser compatibility

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