Best way to create SEO friendly URI string

Question

The method should allows only "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-" chars in URI strings.

What is the best way to make nice SEO URI string?

This sounds like a terrible idea. Consider [encoding the URL](http://download.oracle.com/javase/1.5.0/docs/api/java/net/URLEncoder.html) instead. — moinudin, Jan 02 '11 at 23:19
@marcog: It sounds a lot like what SO does to generate SEO-friendly URLs from titles. Mind you, I'd be very tempted to just replace all non-alnum char sequences with a single hyphen; same general effect (if perhaps slightly different in edge cases) but easier to understand. — Donal Fellows, Jan 02 '11 at 23:27
@Donal Oh, right. Surely you'd generate a random string from the set of allowed characters though? — moinudin, Jan 02 '11 at 23:28
@marcog: What SO does is put that part (which actually *doesn't matter*) on the end of the URL; the path fragment before is an ID which is what actually locates the question. It's safe to use user input for this because the sanitization is defined in terms of a severe whitelist of characters. (Random string? Where did that come from?) — Donal Fellows, Jan 03 '11 at 20:01
@Donal Okay, I see what you're referring to. I thought you meant the ID, e.g. 4581025 for this question. Thanks for clarifying! — moinudin, Jan 03 '11 at 20:09

score 36 · Accepted Answer · answered Jan 03 '11 at 01:37

This is what the general consensus is:

Lowercase the string.
```
string = string.toLowerCase();
```

Normalize all characters and get rid of all diacritical marks (so that e.g. é, ö, à becomes e, o, a).

string = Normalizer.normalize(string, Form.NFD).replaceAll("\\p{InCombiningDiacriticalMarks}+", "");

Replace all remaining non-alphanumeric characters by - and collapse when necessary.
```
string = string.replaceAll("[^\\p{Alnum}]+", "-");
```

So, summarized:

public static String toPrettyURL(String string) {
    return Normalizer.normalize(string.toLowerCase(), Form.NFD)
        .replaceAll("\\p{InCombiningDiacriticalMarks}+", "")
        .replaceAll("[^\\p{Alnum}]+", "-");
}

Also recommend removing leading and trailing punctuation. // remove trailing punctuation .replaceAll("[^a-z0-9]+$", "") // remove leading punctuation .replaceAll("^[^a-z0-9]+", ""); — Jason Thrasher, May 06 '12 at 18:24

score 4 · Answer 2 · answered Jan 02 '11 at 23:20

The following regex will do the same thing as your algorithm. I'm not aware of libraries for doing this type of thing.

String s = input
.replaceAll(" ?- ?","-") // remove spaces around hyphens
.replaceAll("[ ']","-") // turn spaces and quotes into hyphens
.replaceAll("[^0-9a-zA-Z-]",""); // remove everything not in our allowed char set

score 1 · Answer 3 · edited May 23 '17 at 10:29

These are commonly called "slugs" if you want to search for more information.

You may want to check out other answers such as How can I create a SEO friendly dash-delimited url from a string? and How to make Django slugify work properly with Unicode strings?

They cover C# and Python more than javascript but have some language-agnostic discussion about slug conventions and issues you may face when making them (such as uniqueness, unicode normalization problems, etc).

Best way to create SEO friendly URI string

What is the best way to make nice SEO URI string?

3 Answers3

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