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PerformanceEntry.toJSON()

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toJSON() 方法是一个串行器( serializer ); 它返回{domxref("PerformanceEntry","performance entry")}}对象的一个JSON表示形式。

Syntax

const json = perfEntry.toJSON();

Arguments

None
 

Return value

json
A JSON object that is the serialization of the PerformanceEntry object.

Example

The following example shows the use of the toJSON() method.

function run_PerformanceEntry() {
  log("PerformanceEntry support ...");

  if (performance.mark === undefined) {
    log("... performance.mark Not supported");
    return;
  }

  // Create some performance entries via the mark() method
  performance.mark("Begin");
  do_work(50000);
  performance.mark("End");

  // Use getEntries() to iterate through the each entry
  var p = performance.getEntries();
  for (var i=0; i < p.length; i++) {
    log("Entry[" + i + "]");
    check_PerformanceEntry(p[i]);
  }
}
function check_PerformanceEntry(obj) {
  var properties = ["name", "entryType", "startTime", "duration"];
  var methods = ["toJSON"];

  for (var i=0; i < properties.length; i++) {
    // check each property
    var supported = properties[i] in obj;
    if (supported)
      log("..." + properties[i] + " = " + obj[properties[i]]);
    else 
      log("..." + properties[i] + " = Not supported");
  }
  for (var i=0; i < methods.length; i++) {
    // check each method
    var supported = typeof obj[methods[i]] == "function";
    if (supported) {
      var js = obj[methods[i]]();
      log("..." + methods[i] + "() = " + JSON.stringify(js));
    } else {
      log("..." + methods[i] + " = Not supported");
    }
  }
}

Specifications

Specification Status Comment
Performance Timeline Time Level 2
toJSON
Editor's Draft Initial definition of toJSON() method.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
toJSON() (Yes) (Yes) 未实现 未实现 未实现
Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
toJSON() (Yes) 25.0 (25.0) 1.2 (25.0) 未实现 (Yes) 未实现

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