Help refactor a small piece of Javascript code which identifies user's referrer source

问题

I've written the following small piece of javascript (Based on the excellent parseURI function) to identify where the user originated from. I am new to Javascript, and although the code below works, was wondering if there is a more efficient method of achieving this same result?

try {
        var path = parseUri(window.location).path;

        var host = parseUri(document.referrer).host;
        if (host == '') {
                alert('no referrer');
                }

        else if (host.search(/google/) != -1 || host.search(/bing/) != -1 || host.search(/yahoo/) != -1) {
                alert('Search Engine');
                }
        else {
                alert('other');
                }
        } 

catch(err) {}

回答1:

You can simplify the host check using alternative searches:

else if (host.search(/google|bing|yahoo/) != -1 {

I'd also be tempted to test document referrer before extracting the host for your "no referrer" error.

(I've not tested this).

回答2:

I end up defining a function called set in a lot of my projects. It looks like this:

function set() {
    var result = {};
    for (var i = 0; i < arguments.length; i++)
        result[arguments[i]] = true;
    return result;
}

Once you've got the portion of the hostname that you're looking for...

// low-fi way to grab the domain name without a regex; this assumes that the
// value before the final "." is the name that you want, so this doesn't work
// with .co.uk domains, for example
var domain = parseUri(document.referrer).host.split(".").slice(-2, 1)[0];

...you can elegantly test your result against a list using JavaScript's in operator and the set function we defined above:

if (domain in set("google", "bing", "yahoo"))
    // do stuff

More info:

• http://laurens.vd.oever.nl/weblog/items2005/setsinjavascript/

来源：https://stackoverflow.com/questions/5247207/help-refactor-a-small-piece-of-javascript-code-which-identifies-users-referrer