Alternative to a million IF statements

Question

Using JavaScript I am pulling names out of webpage and stringing them together somehow (probably going with an array). Once I gather all the names together I need to make another string that gives all the email addresses of the names. The email addresses are not on the webpage so I will have to list every possible thisName=thisEmail in my script somehow. I was about to approach this with making a bazillion if statements but I thought there has to be a more efficient way. Any suggestions?

var x = getElementById("names");
var name = x.InnerHTML;
var email;
if (name == 'Steve'){ email == 'steve462@gmail.com'; }
if (name == 'Bob'){ email == 'duckhunter89@gmail.com'; }
....

Based on the limited example you provided, the `email` seems to just be the lower-case version of the name with `@gmail.com`, appended to the end. If that's the case, you don't need any kind of control structure. — Anthony Grist, Apr 05 '12 at 13:03
@AnthonyGrist Sorry I gave a bad example. The emails are more random than just the first name `@gmail.com` — Jonathan Eckman, Apr 05 '12 at 13:23

Bergi · Accepted Answer · 2012-04-05T13:16:30.133

A switch statement, as your code is only if-elses :-)

No, honestly. The best thing would be if you'd find a simple algorithm to create an email address from any given name, like

function mail(name) {
    return name.toLowerCase() + "@gmail.com";
}
var email = mail("Bob") // example usage

If they differ to much, you might use an object as a key-value-map:

var mails = {
    "Steve": "steve@gmail.com",
    "Bob": "bob1@freemail.org",
    ...
}
var email = mails[name];

You could also combine those, if you have to determine which algorithm you need to use:

var map = [{
    algorithm: function(name) { return name+"@something"; },
    names: ["Steve", "Bob", ...]
},{
    algorithm: function(name) { return "info@"+name+".org"; },
    names: ["Mark", ...]
}];
for (var i=0; i<map.length; i++)
    if (map[i].names.indexOf(name) > -1) {
        var email = map[i].algorithm(name);
        break;
    }

or when it is a bit simpler:

var domains = {
    "gmail.com": ["Steve", "Bob", ...],
    "free.xxx": ["Mark", ...],
    ...
};
for (var domain in domains)
    if (domains[domain].indexOf(name) > -1)
        var email = name.toLowerCase()+"@"+domain;
        break;
    }

Just try to reduce the amount of data to deliver to the client as much as you can.

score 2 · Answer 2 · answered Apr 05 '12 at 13:04

2

You can store all the email address in an associative array like

pseudo code

var emailsList = ["steve" => "steve@gmail.com", "bob" => "bob@gmail.com"];
then email = emailsList[name]; will solve your problem

answered Apr 05 '12 at 13:04

Sandeep Manne

6,030
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only that this is not a javascript "associative array". – Bergi Apr 05 '12 at 13:20

Paul · Answer 3 · 2012-04-05T13:10:17.803

You could create an object in advance:

var name_email_map = {
 "Steve": "steve@gmail.com",
 "Bob": "bob@gmail.com",
 "John": "j7hogli123123@telus.net"
}

This would be easy to output from some server side language with a JSON library for whatever language you're using. There is a list of JSON libraries at the bottom of this page: http://www.json.org/

If you're using PHP on the server side you can just json_encode an associative array, which you may have selected from a database.

var name = 'Bob'; //x.innerHTML;
var email = name_email_map[name];
alert(email); // Alerts bob@gmail.com
alert(name_email_map['John']); // Alerts j7hogli123123@telus.net

Alternative to a million IF statements

3 Answers3

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