How do I correctly apply regex so array does not have empty string at the start

Question

I'm struggling with a regex.

I am able to split the string at the required location, but when it is added to an array, the array has an empty string at the start.

// This is the string I am wanting to split.
// I want the first 4 words to be separated from the remainder of the string
const chatMessage = "This is a string that I want to split";

// I am using this regex
const r = /(^(?:\S+\s+\n?){4})/;

const chatMessageArr = chatMessage.split(r);

console.log(chatMessageArr);

It returns:

[ '', 'This is a string ', 'that I want to split' ]

But need it to return:

[ 'This is a string ', 'that I want to split' ]

What have you tried so far to solve this on your own? .slice(), a different regex, ... — Andreas
– Andreas, Commented Mar 24, 2021 at 15:46

Tim Biegeleisen · Accepted Answer · 2021-03-24 15:45:55Z

1

I wouldn't use string split here, I would use a regex replacement:

var chatMessage = "This is a string that I want to split";
var first = chatMessage.replace(/^\s*(\S+(?:\s+\S+){3}).*$/, "$1");
var last = chatMessage.replace(/^\s*\S+(?:\s+\S+){3}\s+(.*$)/, "$1");
console.log(chatMessage);
console.log(first);
console.log(last);

answered Mar 24, 2021 at 15:45

Tim Biegeleisen

526k32 gold badges323 silver badges399 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

NikiT Over a year ago

So would you suggest the below to place the now two separate strings into one array? chatMessageArr.push(chatMessage.replace(/^\s*(\S+(?:\s+\S+){3}).*$/, "$1")); chatMessageArr.push(chatMessage.replace(/^\s*\S+(?:\s+\S+){3}\s+(.*$)/, "$1"));

Tim Biegeleisen Over a year ago

Yes, you could do that. There might also be some canonical way to split a string in JavaScript on a single nth occurrence of some pattern. This might be a better alternative to the answer I gave you above.

Barmar · Accepted Answer · 2021-03-24 16:03:29Z

0

Add a second capture group to the regexp and use .match() instead of .split().

// This is the string I am wanting to split.
// I want the first 4 words to be separated from the remainder of the string
const chatMessage = "This is a string that I want to split";

// I am using this regex
const r = /(^(?:\S+\s+\n?){4})(.*)/;

const chatMessageArr = chatMessage.match(r);
chatMessageArr.shift(); // remove the full match

console.log(chatMessageArr);

answered Mar 24, 2021 at 16:03

Barmar

789k57 gold badges554 silver badges669 bronze badges

Collectives™ on Stack Overflow

How do I correctly apply regex so array does not have empty string at the start

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related