Regular expression to replace words preserving spaces

Question

I'm trying to develop a function in javascript that get a phrase and processes each word, preserving whiteSpaces. It would be something like this:

properCase(' hi,everyone just testing') => ' Hi,Everyone Just Testing'

I tried a couple of regular expressions but I couldn't find the way to get just the words, apply a function, and replace them without touching the spaces.

I'm trying with

' hi,everyone just testing'.match(/([^\w]*(\w*)[^\w]*)?/g, 'x') [" hi,", "everyone ", "just ", "testing", ""]

But I can't understand why are the spaces being captured. I just want to capture the (\w*) group. also tried with /(?:[^\w]*(\w*)[^\w]*)?/g and it's the same...

Try using word boundaries \b\w+\b

elclanrs
– elclanrs

2014-02-03 04:32:46 +00:00
Commented Feb 3, 2014 at 4:32 — elclanrs
– elclanrs, Commented Feb 3, 2014 at 4:32
both elclanrs and ooga are correct! thanks a lot

opensas
– opensas

2014-02-03 05:13:19 +00:00
Commented Feb 3, 2014 at 5:13 — opensas
– opensas, Commented Feb 3, 2014 at 5:13

Michal Brašna · Accepted Answer · 2014-02-03 05:17:10Z

3

What about something like

' hi,everyone just testing'.replace(/\b[a-z]/g, function(letter) { return letter.toUpperCase(); });

If you want to process each word, you can use

' hi,everyone just testing'.replace(/\w+/g, function(word) { // do something with each word like return word.toUpperCase(); });

edited Feb 3, 2014 at 5:17

answered Feb 3, 2014 at 4:33

Michal Brašna

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3 Comments

opensas Over a year ago

Yeap, your code works great, but ProperCase was just a simplified example, I need to run a function on the whole word, not just the letter, anyway +1 because I wasn't clear enough...

Michal Brašna Over a year ago

I updated my answer to show how to process each word.

opensas Over a year ago

Great, I even noticed that with just \w+ is enough, no need for the word boundaries markers, thanks a lot

Felix Kling · Accepted Answer · 2014-02-03 04:38:29Z

When you use the global modifier (g), then the capture groups are basically ignored. The returned array will contain every match of the whole expression. It looks like you just want to match consecutive word characters, in which case \w+ suffices:

>>> ' hi,everyone just testing'.match(/\w+/g) ["hi", "everyone", "just", "testing"]

Thanks a lot Felix, your answer is correct. I gave it to Michal because he answered first.

acarlon · Accepted Answer · 2014-02-03 04:49:25Z

See here: jsfiddle

function capitaliseFirstLetter(match) { return match.charAt(0).toUpperCase() + match.slice(1); } var myRe = /\b(\w+)\b/g; var result = "hi everyone, just testing".replace(myRe,capitaliseFirstLetter); alert(result);

Matches each word an capitalizes.

vol7ron · Accepted Answer · 2014-02-03 05:37:09Z

I'm unclear about what you're really after. Why is your regex not working? Or how to get it to work? Here's a way to extract words and spaces in your sentence:

var str = ' hi,everyone just testing'; var words = str.split(/\b/); // [" ", "hi", ",", "everyone", " ", "just", " ", "testing"] words = word.map(function properCase(word){ return word.substr(0,1).toUpperCase() + word.substr(1).toLowerCase(); }); var sentence = words.join(''); // back to original

Note: When doing any string manipulation, replace will be faster, but split/join allows for cleaner, more descriptive code.

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