I looked at some questions and answers about capitalize in StackOverflow but could not find answer about my problem.

I would like to capitalize first letter of each word in a string only if word lengh > 2.

My temporary solution was:

var str =  str.toLowerCase().replace(/\b[a-z]/g, function (letter) {
                return letter.toUpperCase();
            }).replace(/\b\w{1,2}\b/g, function (letter) {
                return letter.toLowerCase();
            });

There is a solution that can unite the two regex in one?

I looked at some questions and answers about capitalize in StackOverflow but could not find answer about my problem.

I would like to capitalize first letter of each word in a string only if word lengh > 2.

My temporary solution was:

var str =  str.toLowerCase().replace(/\b[a-z]/g, function (letter) {
                return letter.toUpperCase();
            }).replace(/\b\w{1,2}\b/g, function (letter) {
                return letter.toLowerCase();
            });

There is a solution that can unite the two regex in one?

• javascript
• regex

• What should happen in edge cases like "i want to be 'titelised'"? Should the quoted word remain unchanged? – Xotic750 Commented Jun 19, 2013 at 21:17
• Or others such as "19th amendment" or "train19", unfortunately language is irregular. – Xotic750 Commented Jun 19, 2013 at 21:26
• @Xotic750 The functionality is for to format names. – Conrado Fonseca Commented Jun 19, 2013 at 22:41
• 1 Aha, that gives us a little more insight into what you were trying to achieve, of course there are still many 2 character names out there, especially Chinese, "jo", "ia", "li" are just some examples. So I assume whitespace boundries would be enough in your use case? – Xotic750 Commented Jun 19, 2013 at 22:53

6 Answers 6

This must do the job:

str = str.toLowerCase().replace(/\b[a-z](?=[a-z]{2})/g, function(letter) {
    return letter.toUpperCase(); } );

or to deal with unicode letters:

str = str.toLowerCase().replace(/(?<!\p{L})\p{L}(?=\p{L}{2})/gu, m => m.toUpperCase());

[EDIT]

The first above example is a little naive since it assumes that there is only letters in the string, and doesn't take account that a word boundary \b can match the limit between a word character [a-zA-Z0-9_] and a non word character or an anchor. Thus, to be more rigorous, it's better to write:

str = str.toLowerCase().replace(/([^a-z]|^)([a-z])(?=[a-z]{2})/g, function(_, g1, g2) {
    return g1 + g2.toUpperCase(); } );

If you want to do the same but this time, including the first letter of the string (whatever the number of letters after) you can use this:

str = str.toLowerCase().replace(/([^a-z])([a-z])(?=[a-z]{2})|^([a-z])/g, function(_, g1, g2, g3) {
    return (typeof g1 === 'undefined') ? g3.toUpperCase() : g1 + g2.toUpperCase(); } );

Try this:

var str = str.toLowerCase().replace(/\b\w{3,}/g, function (l) {
    return l.charAt(0).toUpperCase() + l.slice(1);
});

Here's a simpler solution which does the job.

const capitalize = (str) =>
  str.toLowerCase().replace(/\w{3,}/g, (match) =>
    match.replace(/\w/, (m) => m.toUpperCase()));

Maybe use a function to make it more clean

var capitalize1st = function(str){
    str = str || '';

    // string length must be more than 2
    if(str.length<3){
        return str;
    }

    return str[0].toUpperCase()+str.slice(1);
}

var splitWordsAndCap1st = function(str){
    str = str || '';

    var words = str.match(/\S+/g);

    for(var i=0;i<words.length;i++){
        words[i] = capitalize1st(words[i]);
    }

    return words.join(' ');
}

splitWordsAndCap1st("I would like to capitalize first letter of each word in a string");

No need for regex (just one small one to capture whitespace), you could do this

Javascript

function titleCaseLengthGt2(string) {
    var array = string.split(/(\s+)/),
        length = array.length,
        i = 0,
        word;

    while (i < length) {
        //array[i] = array[i].toLowerCase(); // make words lowercased first if you want
        word = array[i];
        if (word.length > 2) {
            array[i] = word.charAt(0).toUpperCase() + word.slice(1);
        }

        i += 1;
    }

    return array.join("");
}

console.log(titleCaseLengthGt2("i  want  to  be  titelised"));

Output

i  Want  to  be  Titelised 

on jsfiddle

To capitalize first letter of each word in a string if word length > 2, I use for english text:

l_text = l_text.toLowerCase().replace(/(?=\b)([a-z])(?=[a-z]{2})/g, 
     function(g0) {return (g0.toUpperCase());});

Often in real life the rule "word length > 2" is not enough.

To capitalize town names in french I have to exclude some words like in this sample:

l_text = "Bourg-en-Bresse, NEUILLY SUR SEINE, enghien-les-bains";
l_text = l_text.toLowerCase().replace(/(?=\b)(?!(?:d|en|les|sous|sur)\b)([a-z])/g,
     function(g0) {return (g0.toUpperCase());});

For a more sophisticated situation, you may combine the negative lookahead assertion (?!(:|en|les|sous|sur)\b) and the positive lookahead assertion (?=[a-z]{2}).

To deal with non standard word boundary and characters out of a-z range, you may use a word boundary and characters set specific to the context:

/(?:^|[\s'\-])(?!(?:d|en|les|sous|sur)[\s'\-])([a-zàâéèêïôùûç])/g