javascript extract hashtags from strings

You can use String.match, with regex #\w+:

var str = `
type 1. #World is a #good #place to #live.
type 2. #World#place#live.`

var matches = str.match(/#\w+/g)

console.log(matches)

\w+ matches any word character [a-zA-Z0-9_] more than once, so you might want to tweak that.

Once you have the matches in an array you can rearrange them to your likes.

The pattern #(\S*) will match a # followed by 0+ times a non whitespace character in a captured group. That would match a single # as well. The string #World#place#live. contains no whitespace character so the whole string will be matched.

You could match them instead by using a negated character class. Match #, followed by a negated character class that matches not a # or a whitespace character.

#[^#\s]+

Regex demo

const strings = [
  "#World is a #good #place to #live.",
  "#World#place#live."

];
let pattern = /#[^#\s]+/g;

strings.forEach(s => {
  console.log(s.match(pattern));
});

How about that using regex /#([\w]+\b)/gm and join by space like below to extract #hastags from your string? OR you can use str.replace(/\b#[^\s#]+/g, " $&") as commented by @Wiktor

function findHashTags(str) {  
    var regex = /#([\w]+\b)/gm;
    var matches = [];
    var match;

    while ((match = regex.exec(str))) {
        matches.push(match[0]);
    }
    return matches;
}
let str1 = "#World is a #good #place to #live."
let str2 = "#World#place#live";
let res1 = findHashTags(str1);
let res2 = findHashTags(str2);
console.log(res1.join(' '));
console.log(res2.join(' '));