freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/regular-expressions/match-beginning-string-patterns.md

id, title, challengeType, forumTopicId

id	title	challengeType	forumTopicId
587d7db7367417b2b2512b9d	Match Beginning String Patterns	1	301349

Description

Prior challenges showed that regular expressions can be used to look for a number of matches. They are also used to search for patterns in specific positions in strings. In an earlier challenge, you used the caret character (^) inside a character set to create a negated character set in the form [^thingsThatWillNotBeMatched]. Outside of a character set, the caret is used to search for patterns at the beginning of strings.

let firstString = "Ricky is first and can be found.";
let firstRegex = /^Ricky/;
firstRegex.test(firstString);
// Returns true
let notFirst = "You can't find Ricky now.";
firstRegex.test(notFirst);
// Returns false

Instructions

Use the caret character in a regex to find "Cal" only in the beginning of the string rickyAndCal.

Tests

tests:
  - text: Your regex should search for <code>"Cal"</code> with a capital letter.
    testString: assert(calRegex.source == "^Cal");
  - text: Your regex should not use any flags.
    testString: assert(calRegex.flags == "");
  - text: Your regex should match <code>"Cal"</code> at the beginning of the string.
    testString: assert(calRegex.test("Cal and Ricky both like racing."));
  - text: Your regex should not match <code>"Cal"</code> in the middle of a string.
    testString: assert(!calRegex.test("Ricky and Cal both like racing."));

Challenge Seed

let rickyAndCal = "Cal and Ricky both like racing.";
let calRegex = /change/; // Change this line
let result = calRegex.test(rickyAndCal);

Solution

let rickyAndCal = "Cal and Ricky both like racing.";
let calRegex = /^Cal/; // Change this line
let result = calRegex.test(rickyAndCal);