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4 ways to Compare Strings in JavaScript

Coderslang: Become a Software Engineer
Teaching you to code at js.coderslang.com - JavaScript, HTML, CSS, Node.js, React.js, React Native
Originally published at learn.coderslang.com ・2 min read

In this short JS tutorial, you’ll learn how to compare strings and see code examples.

Strict equality

To determine whether the strings are equal, you can use the strict equality operator ===. It returns false if the strings are different and true, if they’re the same.

const s1 = 'learn';
const s2 = 'today';

console.log(s1 === 'learn');  // true
console.log(s1 === s2);       // false
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Comparing the strings using strict equality === always analyzes the case of the letters, meaning that capital letters are different from the small ones.

const s1 = 'javascript';
const s2 = 'Javascript';

console.log(s1 === s2); // false
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Case-insensitive string comparison

If you want to do a case insensitive comparison of the strings in JavaScript, you can turn both strings to lowercase and compare them using a strict equality operator afterward.

const s1 = 'javascript';
const s2 = 'Javascript';

console.log(s1.toLowerCase() === s2.toLowerCase()); // true
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Comparing the length of JavaScript strings

If you need to find which of two strings is longer, then the operators "greater than" and "lower than" won’t suit you well. They compare the characters of a string in alphanumeric order one by one and consider the length of the strings at the very end.

const s1 = 'javascript';
const s2 = 'node.js';

console.log(s1 > s2); // false
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In JS, every string has the length property. By comparing the value of this property in different strings, we’ll get to know which of them is longer.

const s1 = 'javascript';
const s2 = 'node.js';

console.log(s1.length > s2.length); // true
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Check if a string contains another string

To check if one string is a substring of another in JavaScript, there’s a built-in function includes. Remember, the function contains exists in Java, but it’s deprecated and replaced by includes in JavaScript.

const s1 = 'javascript';
const s2 = 'python';

console.log(s1.includes('script')); // true
console.log(s2.includes('script')); // false
console.log(s1.contains('java'))    // ERROR! .contains is not a function
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Read more JavaScript tutorials or Learn Full-Stack JS from scratch!

Discussion (2)

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z00md profile image
z00md

Title is a bit misleading. Instead of saying 4 ways of comparing strings, it should be 4 common string operations.

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coderslang profile image
Coderslang: Become a Software Engineer Author • Edited

Your point makes sense, but for the total beginners, it's important to know that strict equality isn't the only way to compare two strings in JS.

And I wrote another article on the common string operations in JS