在这里看到一个例子:

What about the trust issue of never being called? If this is a concern
(and it probably should be!), you likely will need to set up a timeout
that cancels the event. You could make a utility (proof-of-concept
only shown) to help you with that:

function timeoutify(fn,delay) {
    var intv = setTimeout( function(){
            intv = null;
            fn( new Error( "Timeout!" ) );
        }, delay )
    ;

    return function() {
        // timeout hasn't happened yet?
        if (intv) {
            clearTimeout( intv );
            fn.apply( this, arguments );
        }
    };
}

Here's how you use it:

// using "error-first style" callback design
function foo(err,data) {
    if (err) {
        console.error( err );
    }
    else {
        console.log( data );
    }
}

ajax( "http://some.url.1", timeoutify( foo, 500 ) );

请问：
1.timeoutify解决了什么问题？（我能看懂代码）
2.如何理解 set up a timeout that cancels the event. ？