Javascript正则表达式只匹配以特定特殊字符开头的单词

Question

I'm trying to match only words starting with # in javascript, for eg. in the following sample text, only #these should match.

I need to match only words like #these. Ignore the ones like @#this , !#this and in#ignore.

The closer I got is here,

/(\B(#[a-z0-9])\w+)/gi

Ref: https://regex101.com/r/wU7sQ0/114

Answer 1

Use a whitespace boundary (?:^|\\s) :

 var rx = /(?:^|\\s)(#[a-z0-9]\\w*)/gi; var s = "I need to match only words like #these. \\nIgnore the ones like @#this , !#this and in#ignore."; var m, res=[]; while (m = rx.exec(s)) { res.push(m[1]); } console.log(res); 

Details :

• (?:^|\\s) - matches the start of string or whitespace
• (#[a-z0-9]\\w*) - Group 1 ( m[1] ): a # , then an alphanumeric char followed with 0 or more word chars (letters, digits, _ symbols).

See the regex demo , pay attention to what texts are captured , rather to the whole matches.

Or trimming each match:

 var rx = /(?:^|\\s)(#[a-z0-9]\\w*)/gi; var s = "I need to match only words like #these. \\nIgnore the ones like @#this , !#this and in#ignore."; var results = s.match(rx).map(function(x) {return x.trim();}); // ES5 // var results = s.match(rx).map(x => x.trim()); // ES6 console.log(results); 

Answer 2

Why not search start or with space before. see regex / #|^#

Answer 3

I little bit changed your regex to get what do you want.

var p = "I need to match only words like #these. Ignore the ones like @#this , !#this and in#ignore."

[^@!a-z$]\#[a-z]+

That will be match only #these, you can exclude whatever you don't want by adding between first square bracket

Answer 4

you can try this,

 txt = "I need to match only words like #these. Ignore the ones like @#this , !#this and in#ignore." console.log(/(^|\\s)(#+\\w+)/g.exec(txt))