Scenario

In this example, we run through all of the possible request headers and try to set them using the XHR's setRequestHeader method. According to the specification, some of these headers are allowed to be set, some should be appended to the current value, and some should be replaced. All browsers follow different rules and none strictly follow the specification.

To see how the common browsers perform, visit http://ajaxref.com/ch3/requestexplorerresults.php