正则表达式匹配的OrgMode标签

Question

I want to write an regex in JavaScript to match the tags in OrgMode format

Example:

• Sample title :tag1:tag2:tag3:

I have tested the following regex but it only matches the first and the last tags (tag1,tag3):

\:\w+\:

Thanks

Answer 1

My guess is that here an expression with start and end anchors might be desired, if we'd be validating:

^((?=:\w+)(:\w+)+):$

Demo 1

 const regex = /^((?=:\\w+)(:\\w+)+):$/gm; const str = `:tag1:tag2:tag3: :tag1:tag2:tag3:tag4: :tag1:tag2:tag3:tag4:tage5: :tag1:tag2:tag3:tag4:tage5`; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); } 

Answer 2

Use

/:(\w+)(?=:)/g

The value you need is inside Group 1. See the regex demo online .

The main point is the (?=:) positive lookahead: it checks (and requires) but does not consume the : to the right of the \\w+ pattern.

See JS demo below:

 var s = "Sample title :tag1:tag2:tag3:"; var reg = /:(\\w+)(?=:)/g; var results = [], m; while(m = reg.exec(s)) { results.push(m[1]); } console.log(results);