jQuery为什么在try / catch中包装XHR对象的创建？

Question

If I had to write my own cross-browser AJAX function without jQuery (which I do), I would do this:

var getXHR = function() {
  if (window.XMLHttpRequest) {
    return new XMLHttpRequest();
  } else if (window.ActiveXObject) {
    return new ActiveXObject('Microsoft.XMLHTTP');
  }
}

But while digging through jQuery's source code , I noticed this:

function createStandardXHR() {
  try {
    return new window.XMLHttpRequest();
  } catch( e ) {}
}
function createActiveXHR() {
  try {
    return new window.ActiveXObject( "Microsoft.XMLHTTP" );
  }
}

Then:

createStandardXHR() || createActiveXHR();

Why do the jQuery developers just call the object constructors directly inside of a try/catch block, rather than using feature detection. I imagine a try/catch is slower than a simple if check. What is the benefit?

Answer 1

Your method is good.
After reading the code, I think the developers of jQuery uses this trick to create the Request object and test !this.isLocal && /^(get|post|head|put|delete|options)$/i.test( this.type ) && in a single statement without error.