var times = 0;
var somedata = 1;
function f(){
    console.log("哎呀，2 个请求都到啦")
}
$(function(){
    var i;
    for (i = 0; i < 2; i++){
        $.post(
            'test.PHP',
            somedata,
            function (data) {
                times++
                if (times === 2) f()
            }
        )
    }
})

$.when( $.ajax( "/page1.PHP" ),$.ajax( "/page2.PHP" ) ).done(function( a1,a2 ) {
  // a1 and a2 are arguments resolved for the page1 and page2 ajax requests,respectively.
  // Each argument is an array with the following structure: [ data,statusText,jqXHR ]
  var data = a1[ 0 ] + a2[ 0 ]; // a1[ 0 ] = "Whip",a2[ 0 ] = " It"
  if ( /Whip It/.test( data ) ) {
    alert( "We got what we came for!" );
  }
});