如何从jQuery的ajax请求中删除X-Requested-With

$.ajax({
url: 'http://www.zhangruifeng.com',
beforeSend: function( xhr ) {
xhr.setRequestHeader('X-Requested-With', {toString: function(){ return ''; }});
},
success: function( data ) {
if (console && console.log){
console.log( 'Got data without the X-Requested-With header' );
}
}
});

if (request.getHeader("x-requested-with") != null
&& request.getHeader("x-requested-with").equalsIgnoreCase("XMLHttpRequest")) {
//异步请求
}else{

}