Get first letter of each word in a string, in JavaScript

Question

How would you go around to collect the first letter of each word in a string, as in to receive an abbreviation?

Input: "Java Script Object

Answer 1

Alternative 1:

you can also use this regex to return an array of the first letter of every word

/(?<=(\s|^))[a-z]/gi

(?<=(\s|^)) is called positive lookbehind which make sure the element in our search pattern is preceded by (\s|^).

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so, for your case:

// in case the input is lowercase & there's a word with apostrophe

const toAbbr = (str) => {
  return str.match(/(?<=(\s|^))[a-z]/gi)
            .join('')
            .toUpperCase();
};

toAbbr("java script object notation"); //result JSON

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(by the way, there are also negative lookbehind, positive lookahead, negative lookahead, if you want to learn more)

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Alternative 2:

match all the words and use replace() method to replace them with the first letter of each word and ignore the space (the method will not mutate your original string)

// in case the input is lowercase & there's a word with apostrophe    

const toAbbr = (str) => {
  return str.replace(/(\S+)(\s*)/gi, (match, p1, p2) => p1[0].toUpperCase());
};

toAbbr("java script object notation"); //result JSON

// word = not space = \S+ = p1 (p1 is the first pattern)
// space = \s* = p2 (p2 is the second pattern)