freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/regular-expressions/find-characters-with-lazy-matching.english.md

id, title, challengeType, forumTopicId

id	title	challengeType	forumTopicId
587d7db6367417b2b2512b9b	Find Characters with Lazy Matching	1	301341

Description

In regular expressions, a greedy match finds the longest possible part of a string that fits the regex pattern and returns it as a match. The alternative is called a lazy match, which finds the smallest possible part of the string that satisfies the regex pattern. You can apply the regex /t[a-z]*i/ to the string "titanic". This regex is basically a pattern that starts with t, ends with i, and has some letters in between. Regular expressions are by default greedy, so the match would return ["titani"]. It finds the largest sub-string possible to fit the pattern. However, you can use the ? character to change it to lazy matching. "titanic" matched against the adjusted regex of /t[a-z]*?i/ returns ["ti"]. Note
Parsing HTML with regular expressions should be avoided, but pattern matching an HTML string with regular expressions is completely fine.

Instructions

Fix the regex /<.*>/ to return the HTML tag <h1> and not the text "<h1>Winter is coming</h1>". Remember the wildcard . in a regular expression matches any character.

Tests

tests:
  - text: The <code>result</code> variable should be an array with <code>&lt;h1&gt;</code> in it
    testString: assert(result[0] == '<h1>');
  - text: <code>myRegex</code> should use lazy matching
    testString: assert(/\?/g.test(myRegex));
  - text: <code>myRegex</code></code> should not include the string 'h1'
    testString: assert(!myRegex.source.match('h1'));

Challenge Seed

let text = "<h1>Winter is coming</h1>";
let myRegex = /<.*>/; // Change this line
let result = text.match(myRegex);

Solution

let text = "<h1>Winter is coming</h1>";
let myRegex = /<.*?>/; // Change this line
let result = text.match(myRegex);