Changing form submit type with jQuery

I have a Google Instant style jQuery script that displays search results as the user types in the search box. However, I want my script to make the user press enter the first time they want to submit a query but then after that for the instant search script to work.

How can I do this with the code I have posted below? I hope you can understand my question.

$('input').keyup(function(){
    query=$(this).val();
    url='/'+type+'/'+query+'/';
    window.location.hash=开发者_如何学编程''+type+'/'+query+'/';
    document.title=$(this).val()+' - My Search Script';
    $('#results').show();
    if(query==''){
        window.location.hash='';
        document.title='My Search Script';
        $('#results').hide();
    }
    $.ajax({
        type:'GET',
        url:url,
        dataType:'html',
        success:function(results) {
            $('#results').html(results);
        }
    });
});

---

var pressed = false;
    $('input').keyup(function(event){
       if (event.keyCode == '13' || pressed)
       {
       pressed = true;
        query=$(this).val();
        url='/'+type+'/'+query+'/';
        window.location.hash=''+type+'/'+query+'/';
        document.title=$(this).val()+' - My Search Script';
        $('#results').show();
        if(query==''){
            window.location.hash='';
            document.title='My Search Script';
            $('#results').hide();
        }
        $.ajax({
            type:'GET',
            url:url,
            dataType:'html',
            success:function(results) {
                $('#results').html(results);
            }
        });
       }
    });

this will only work for enter key

---

While the user has not pressed enter, the script will do nothing. Once the user presses enter, this will start to update the search each time a key is pressed:

var hasPressedEnter = false;
$('input').keyup(function(event){
    if (event.keyCode == 13 /* ENTER */) {
        hasPressedEnter = true;
    }
    if (!hasPressedEnter) {
        return;
    }
    // rest of the code here