How to split an array after a specified regex pattern in JavaScript

Question

I would like to split a string of text into an array of sentences without loosing the punctuation mark.

var string = 'This is the first sentence. This is another sentence! This is a question?' 
var splitString = string.split(/[!?.] /);
splitString  
  => ["This is the first sentence", "This is another sentence", "This is a question?"]

Only the last punctuation mark(?) is kept. What is the best way to split after the punctuation marks on all the sentences so that splitString returns the following instead?

["This is the first sentence.", "This is another sentence!", "This is a question?"]

Anyways, it's easily googleable by "javascript string split keep delimiter" — pumbo
– pumbo, Commented Mar 28, 2017 at 5:44

gyre · Accepted Answer · 2017-03-28 06:19:05Z

3

Instead of using split to target where you want to break your text, you can use String#match with a global regular expression and target the text you want to keep:

var splitString = string.match(/\S.+?[!?.]/g)

This avoids the need to use look-behinds, which are unsupported in JavaScript's regex flavor as of now, or additional calls to methods like Array#filter:

var string = 'This is the first sentence. This is another sentence! Is this a question?'

var splitString = string.match(/\S.+?[!?.]/g)

console.log(splitString)

edited Mar 28, 2017 at 6:19

answered Mar 28, 2017 at 5:44

gyre

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Comments

RomanPerekhrest · Accepted Answer · 2017-03-28 05:59:01Z

1

Few approaches:

The solution using String.prototype.match() function to get an array of sentences:

var string = 'This is the first sentence. This is another sentence! This is a question?',
    items = string.match(/\S[^.!?]+[.?!]/g);

console.log(items);

The alternative solution using String.prototype.split() function would look like below:

var string = 'This is the first sentence. This is another sentence! This is a question?',
    items = string.split(/(\S[^.!?]+[.?!])/g).filter(function(s){ return s.trim(); });

console.log(items);

\S[^.!?]+ - will match all characters except specified punctuation chars [^.!?] and starting with non-whitespace character \S

edited Mar 28, 2017 at 5:59

answered Mar 28, 2017 at 5:47

RomanPerekhrest

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4 Comments

gyre Over a year ago

Note that this also matches a leading space at the beginning of some sentences.

RomanPerekhrest Over a year ago

@gyre, can't agree with you

gyre Over a year ago

I see you edited your answer so this is no longer an issue. It was such a small window I did not get a chance to see the changes before commenting :)

RomanPerekhrest Over a year ago

@gyre, yes, I've made the edit right before your comment

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