How do I split a string by whitespace and ignoring leading and trailing whitespace into an array of words using a regular expression?

javascript regex string whitespace removing-whitespace

65,647

Solution 1

If you are more interested in the bits that are not whitespace, you can match the non-whitespace instead of splitting on whitespace.

"  The quick brown fox jumps over the lazy dog. ".match(/\S+/g);

Note that the following returns null:

"   ".match(/\S+/g)

So the best pattern to learn is:

str.match(/\S+/g) || []

Solution 2

" The quick brown fox jumps over the lazy dog. ".trim().split(/\s+/);

Solution 3

Instead of splitting at whitespace sequences, you could match any non-whitespace sequences:

"  The quick brown fox jumps over the lazy dog. ".match(/\S+/g)

65,647

natlee75

Updated on July 05, 2022

Comments

natlee75 almost 2 years
I typically use the following code in JavaScript to split a string by whitespace.
```
"The quick brown fox jumps over the lazy dog.".split(/\s+/);
// ["The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog."]
```
This of course works even when there are multiple whitespace characters between words.
```
"The  quick brown fox     jumps over the lazy   dog.".split(/\s+/);
// ["The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog."]
```
The problem is when I have a string that has leading or trailing whitespace in which case the resulting array of strings will include an empty character at the beginning and/or end of the array.
```
"  The quick brown fox jumps over the lazy dog. ".split(/\s+/);
// ["", "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog.", ""]
```
It's a trivial task to eliminate such empty characters, but I'd rather take care of this within the regular expression if that's at all possible. Does anybody know what regular expression I could use to accomplish this goal?
- DCoder over 11 years
  
  Horses for courses. split is used to split a string, not mutate it. See how to trim a string in JavaScript?.
- Anirudha over 11 years
  
  unfortunately javascript doesnt support lookbehind and even if you had used lookbehind,there would be space in the first split
- natlee75 over 11 years
  
  I never thought of it from that perspective. Thanks for pointing that out!
- Jacques Koorts about 6 years
  
  can't you do a trim() before the split?
natlee75 over 11 years

Thanks for the suggestion. I actually was going to go this route until I remembered that it requires a browser that supports JavaScript 1.8. That's fine for a majority of our users, but we still support older browsers such as Internet Explorer 7 and 8 whose JavaScript engines don't include this functionality.
Andy about 8 years

Watch out, ' '.match(/\S+/g) returns null instead of []!
Andy about 8 years

Watch out, ' '.trim().split(/\s+/) returns [""]!
ibodi about 5 years

I wonder whose solution is faster yours or @Josh 's (if we handle the [""] case).
ibodi about 5 years

I wonder whose solution is faster yours (if we handle the [""] case) or @kennebec 's