// In JavaScript, we use the built-in RegExp object for regular expressions

// This tests whether a pattern matches a string.
let match = /p([a-z]+)ch/.test("peach");
console.log(match);

// We can create a RegExp object for more complex operations
let r = new RegExp("p([a-z]+)ch");

// Here's a match test like we saw earlier
console.log(r.test("peach"));

// This finds the match for the regexp
console.log("peach punch".match(r)[0]);

// This also finds the first match but returns the
// start and end indexes for the match instead of the
// matching text.
let result = "peach punch".match(r);
console.log("idx:", [result.index, result.index + result[0].length]);

// The match method includes information about
// both the whole-pattern matches and the submatches
// within those matches.
console.log("peach punch".match(r));

// To find all matches for a regexp, we use the global flag 'g'
r = new RegExp("p([a-z]+)ch", "g");
console.log("peach punch pinch".match(r));

// Providing a limit to the number of matches
console.log("peach punch pinch".match(r).slice(0, 2));

// The replace method can be used to replace subsets of strings with other values
console.log("a peach".replace(r, "<fruit>"));

// We can also use a function to transform matched text
console.log("a peach".replace(r, (match) => match.toUpperCase()));