Find Word Character in a String with JavaScript RegExp

Regular expressions or RegExp can be used in JavaScript to search for patterns in texts. Searching for a certain character in a string, such as locating all occurrences of a word character, is a typical activity. In this article, we’ll look at how to utilize RegExp in JavaScript to find word characters in a string.

Terminologies:

• Regular expressions: These are basically patterns that are used to match character combinations in strings.
• Character classes: These are basically a group of characters contained in square brackets that can match any of the enclosed characters.
• Word characters: A word character in RegEx is any letter, numeric, or underscore character. The shorthand character class “w” represents it.

Modifiers:

• /g modifier: Indicates to perform a global search.
• /m modifier: Indicates to match the pattern on each line of the string.
• /i modifier: Indicates to perform a case-insensitive search.

Different approaches to finding word characters in a string:

Approach 1: Using the test() method: The simplest way to find word characters in a string is to use the test() method of a regular expression. It returns true if the pattern matches the string and if not then false.

Javascript

const str = "Welcome to GeekforGeeks!";
const regex = /\w/; // Matches any word character

if (regex.test(str)) {
      console.log("Found a word character");
} else {
      console.log("No word characters found");
}

Output:

Found a word character

Approach 2: Using the match() method: Another approach is to use the match() method of a string, which returns an array of all the matches found in the string.

Javascript

const str = "Welcome to GeekforGeeks!";
const regex = /\w/g; // Matches all word characters

const matches = str.match(regex);

if (matches) {
      console.log(`Found ${matches.length} word characters`);
      console.log(matches);
} else {
      console.log("No word characters found");
}

Output:

Found 21 word characters
[
    'W', 'e', 'l', 'c', 'o',
    'm', 'e', 't', 'o', 'G',
    'e', 'e', 'k', 'f', 'o',
     'r', 'G', 'e', 'e', 'k',
    's'
]

Approach 3: Using the exec() method: A third approach is to use the exec() method of a regular expression, which returns an array of the first match found in the string. You can then use a loop to find all the matches.

Javascript

const str = "GeekforGeeks";
const regex = /\w/g; // Matches all word characters

let match;

while ((match = regex.exec(str)) !== null) {
      console.log(`Found word character "${match[0]}"
          at index ${match.index}`);
}

Output:

Found word character "G" at index 0
Found word character "e" at index 1
Found word character "e" at index 2
Found word character "k" at index 3
Found word character "f" at index 4
Found word character "o" at index 5
Found word character "r" at index 6
Found word character "G" at index 7
Found word character "e" at index 8
Found word character "e" at index 9
Found word character "k" at index 10
Found word character "s" at index 11

Examples that are using different modifiers:

Using the /g modifier: In this example, we can perform a full global search to find word characters in a string is to use the test() method of a regular expression.It returns true if the pattern matches the string and if not then false.

Javascript

const str = "Welcome to GeekforGeeks!";
const regex = /\w/; // Matches any word character

console.log(regex.test(str));

Output:

true

Using the /m modifier: This is similar to the previous modifier, the only difference is that it performs a search on each line of the string. The example below returns true if the pattern matches the string and if not then false.

Javascript

const str = 'Welcome to\nGeekforGeeks\nWebsite';
const regex = /GeekforGeeks/m;

console.log(regex.test(str));

Output:

true

Using the /i modifier: This modifier is used when we have to perform a case-insensitive search. This example will return true if the pattern matches the string and if not then false.

Javascript

const str = 'GeekforGeeks is a computer science portal for geeks';
const regex = /geekforgeeks/i;

console.log(regex.test(str));

Output:

true