Loop function using an array

I have a jQuery function using a series of if and else statements. I am wondering if there is a more elegant way I can code this. I am thinking I could create an array with my “hashtag names” and then loop it through a function. However, I am not quite sure how to go about doing that.

setTimeout(function() {
    var i = 0;
    if(window.location.hash == "#" + "somename"){
        var i = 0;
        return scroll(i);
    }

    else if(window.location.hash == "#" + "somethingelse"){
        var i = 1;
        return scroll(i);
    }

    else if(window.location.hash == "#" + "someotherword"){
        var i = 2;
        return scroll(i);
    }

    else if (window.location.hash == "#" + "sometext"){
        var i = 3;
        return scroll(i);
    }
}, 500 );

function scroll(i){
    var title = $('.title').eq(i);
    var top =  $(title).offset().top - 50 ;
    $('html,body').animate({ scrollTop: top }, 'slow');
}

I’m checking to see what hashtag is in the URL, and then scrolling to the part of the page that is related to that hashtag. This method works, but I would like to optimize the if/else part of my code if possible. An array with a loop may not be the best approach. I am open to any ideas.

You can just parse the number right out of the location like this:

setTimeout(function() {
    var matches = window.location.hash.match(/^#page(d+)$/);
    if (matches) {
        scroll(+matches[1] - 1);
    }
}, 500);

OK, now that you’ve changed to random strings, you could use a table lookup like this:

setTimeout(function() {
    var values = {
        "#somename": 1,
        "#somethingelse": 2,
        "#someotherword": 3,
        "#sometext": 4
    };
    var val = values[window.location.hash];
    if (val) {
        scroll(val - 1);
    }
}, 500 );

P.S. Note, there is no reason to return anything from the setTimeout() callback as the return value is not processed by anything which is why I removed the return statement.

The book High Performance JavaScript provides some good advice on looping in JavaScript. To quote it:

Generally speaking, if-else is best used when there are two discrete values or a few different ranges of values for which to test. When there are more than two discrete values for which to test, the switch statement is the most optimal choice. … When there are a large number of discrete values for which to test, both if-else and switch are significantly slower than using a lookup table. (Ch. 4 Algorithms and Flow Control)

Also, instead of calling window.location.hash with each evaluation, copy that value to a local variable and evaluate that. It will improve performance since you won’t keep going back to the DOM to look-up the value.