RegEx to find exactly 4 digits number

Question

I have a text similar to the text below. It contains a 4 digits number that follows either digit- or whitespace and is followed by either ., ?, -digit or whitespace.

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I need to match all of the digits in the first paragraph but none in the second since those digits do not meet my conditions.

Lorem ipsum 3400-digit, sit amet 5000 consectetur adipisicing elit. Natus, explicabo 6700? Itaque iure ipsum laboriosam, ex nemo delectus iste quia cupiditate digit-9134? Iste nam digit-2456 at voluptate est 8456-digit? At excepturi quis voluptatibus 7500.

Lorem ipsum $5000 dolor sit amet consectetur adipisicing elit. Obcaecati tempora dolorum repellat reiciendis cum soluta deserunt ex voluptatibus, nam illum veniam £5550 quidem aperiam sequi, nostrum sed? Quidem eveniet maiores #5550 autem. https://codepen.io/pen/5000/3454

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There are a few similar questions already on StackOverflow. I have gone through some of them(links below), but I still can not do this. Please before marking this question as duplicate, check if your solution finds all the occurrence of the 4 digits number in the first paragraph but none in the second paragraph.

• regular expression to match exactly 5 digits

• Regular expression to match integers up to 9 digits

• RegEx match exactly 4 digits

• JavaScript: \\d{4} RegExp allows more than 4 digits

Answer 1

You may use the following pattern:

/(?:\bdigit-|\s|^)(\d{4})(?=[.?\s]|-digit\b|$)/gi

See the regex demo. You need to get all Group 1 values.

Details

• (?:\bdigit-|\s|^) - either digit- (as a whole word), whitespace or start of string
• (\d{4}) - Group 1: four digits
• (?=[.?\s]|-digit\b|$) - immediately to the right, there must be a ., whitespace, ? , -digit (as a whole word) or end of string. NOTE Without a lookahead, consecutive whitespace-separated matches will be left out.

JS demo:

var strs = ["Lorem ipsum 3400-digit, sit amet 5000 consectetur adipisicing elit. Natus, explicabo 6700? Itaque iure  ipsum laboriosam, ex  nemo delectus iste quia cupiditate digit-9134? Iste nam digit-2456 at voluptate est 8456-digit? At excepturi quis voluptatibus 7500.", "Lorem ipsum $5000  dolor sit amet consectetur adipisicing elit. Obcaecati tempora dolorum repellat reiciendis cum soluta deserunt ex voluptatibus, nam illum veniam £5550 quidem aperiam sequi, nostrum sed? Quidem eveniet maiores #5550 autem. https://codepen.io/pen/5000/3454" ];
var rx = /(?:\bdigit-|\s|^)(\d{4})(?=[.?\s]|-digit\b|$)/gi;
for (var s of strs) {
   var m, res =[];
   while(m=rx.exec(s)) {
     res.push(m[1]);
   }
   console.log(res);
}