freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/regular-expressions/specify-exact-number-of-matches.english.md

id, title, challengeType, isHidden, forumTopicId

id	title	challengeType	isHidden	forumTopicId
587d7db9367417b2b2512ba7	Specify Exact Number of Matches	1	false	301365

Description

You can specify the lower and upper number of patterns with quantity specifiers using curly brackets. Sometimes you only want a specific number of matches. To specify a certain number of patterns, just have that one number between the curly brackets. For example, to match only the word "hah" with the letter a 3 times, your regex would be /ha{3}h/.

let A4 = "haaaah";
let A3 = "haaah";
let A100 = "h" + "a".repeat(100) + "h";
let multipleHA = /ha{3}h/;
multipleHA.test(A4); // Returns false
multipleHA.test(A3); // Returns true
multipleHA.test(A100); // Returns false

Instructions

Change the regex timRegex to match the word "Timber" only when it has four letter m's.

Tests

tests:
  - text: Your regex should use curly brackets.
    testString: assert(timRegex.source.match(/{.*?}/).length > 0);
  - text: Your regex should not match <code>"Timber"</code>
    testString: timRegex.lastIndex = 0; assert(!timRegex.test("Timber"));
  - text: Your regex should not match <code>"Timmber"</code>
    testString: timRegex.lastIndex = 0; assert(!timRegex.test("Timmber"));
  - text: Your regex should not match <code>"Timmmber"</code>
    testString: timRegex.lastIndex = 0; assert(!timRegex.test("Timmmber"));
  - text: Your regex should match <code>"Timmmmber"</code>
    testString: timRegex.lastIndex = 0; assert(timRegex.test("Timmmmber"));
  - text: Your regex should not match <code>"Timber"</code> with 30 <code>m</code>'s in it.
    testString: timRegex.lastIndex = 0; assert(!timRegex.test("Ti" + "m".repeat(30) + "ber"));

Challenge Seed

let timStr = "Timmmmber";
let timRegex = /change/; // Change this line
let result = timRegex.test(timStr);

Solution

let timStr = "Timmmmber";
let timRegex = /Tim{4}ber/; // Change this line
let result = timRegex.test(timStr);