How to Compare Strings in JavaScript

Comparing strings in JavaScript involves determining if two strings are equal, if one string is greater than or less than another, or if they meet certain criteria. JavaScript provides several methods and operators for string comparison. This article explores the most common ways to compare strings in JavaScript.

01. Using the `===` Operator

The === operator is used for strict equality comparison. It checks if two strings are equal in value and type. This is the most common way to compare strings for equality.

let string1 = "Hello";
let string2 = "Hello";
let string3 = "World";

// Check if strings are equal
console.log(string1 === string2); // Output: true
console.log(string1 === string3); // Output: false

In this example, string1 and string2 are equal, while string1 and string3 are not.

02. Using the `!==` Operator

The !== operator checks if two strings are not equal. It returns true if the strings are different and false if they are the same.

let string1 = "Hello";
let string2 = "World";

// Check if strings are not equal
console.log(string1 !== string2); // Output: true

Here, string1 and string2 are not equal, so the result is true.

03. Using the `localeCompare()` Method

The localeCompare() method compares two strings in the current locale. It returns a number indicating whether the string comes before, after, or is the same as another string in the sort order.

let string1 = "apple";
let string2 = "banana";

// Compare strings
console.log(string1.localeCompare(string2)); // Output: -1 (apple comes before banana)

In this example, localeCompare() returns a negative value because string1 ("apple") comes before string2 ("banana").

04. Using the `String.prototype.startsWith()` and `String.prototype.endsWith()` Methods

The startsWith() and endsWith() methods are used to check if a string starts or ends with a specified substring, respectively.

let sentence = "JavaScript is awesome";

// Check if string starts with a specific substring
console.log(sentence.startsWith("JavaScript")); // Output: true

// Check if string ends with a specific substring
console.log(sentence.endsWith("awesome")); // Output: true

These methods are useful for checking prefixes or suffixes in strings.

05. Using the `String.prototype.includes()` Method

The includes() method checks if a string contains a specified substring. It returns true if the substring is found, and false otherwise.

let sentence = "JavaScript is awesome";

// Check if string contains a specific substring
console.log(sentence.includes("is")); // Output: true
console.log(sentence.includes("not")); // Output: false

In this example, includes() helps determine if certain substrings are present within the main string.

Conclusion

Comparing strings in JavaScript can be achieved through various methods and operators, including strict equality checks, inequality checks, locale-based comparisons, and methods for checking specific positions and content. Understanding these techniques helps you effectively manage and manipulate string data in your JavaScript applications.