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A very good W3school tutorial can be found here.

How to add a string only after the last match of a regex.replace (JavaScript)

I’m trying to reformat a list. The function matches certain areas of the original string and reformat those into a "properties" section which has to have the string "—" before and after it. ex,

input:

| name = Malik
| age = 55
| hair = brown

Output:

---
name: malik
age: 55
hair: brown
---

I managed to add "—" before all the matches, but how would I go about only adding the second string after the last match of the replace function?
I tried many approaches but failed horribly. the closest I got was when it added "—" after the first match.

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2

Answers


  1. Chosen as BEST ANSWER
    0

    As expected, after struggling with this issue for literal hours, giving up, posting this question and letting go, I finally got an idea on how to do this and it worked! In case anyone might run into a similar situation what I ended up doing is:

    const totalMatches = string.match(regexp).length; // finds the total amount of matches
let matchIndex = 0; // creates an empty index
string.replace(regexp, function replacer(match, name, value) {
  matchIndex += 1; //adds one each cycle to the index
  let result = `${name}: ${value}n`;
  if (matchIndex === totalMatches) { //adds the string only when it is the last cycle.
    result += "---n";
  }
  return result
})

  2. 0

    Do this as two levels of replacement. Use one regexp to match the entire sequence of lines, so you can add --- around it. Then in the replacement function for that, you can use another replacement to reformat each line.

    const input = `| name = Malik
| age = 55
| hair = brown

| name = James
| age = 24
| hair = blond
`;

const output = input.replace(/(?:^|.*n)+/gm,
  (match) => 
    '---n' +
    match.replace(/^|s*(w+)s*=s*(.*)/gm, '$1: $2') +
    '---n');

console.log(output);
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