JavaScript Program to Perform Case Insensitive String Comparison

In this example, you will learn to write a JavaScript program that will perform case insensitive string comparison.

To understand this example, you should have the knowledge of the following JavaScript programming topics:


Example 1: Using toUpperCase()

// program to perform case insensitive string comparison

const string1 = 'JavaScript Program';
const string2 = 'javascript program';

// compare both strings
let result = string1.toUpperCase() === string2.toUpperCase();

if(result) {
    console.log('The strings are similar.');
} else {
    console.log('The strings are not similar.');
}

Output

The strings are similar.

In the above program, two strings are compared. Here,

  • The toUpperCase() method converts all the string characters to uppercase.
  • === is used to check if both the strings are the same.
  • The if...else statement is used to display the result as per the condition.

Note: You can also use the toLowerCase() method to convert all the strings to lowercase and perform the comparison.


Example 2: Using RegEx

// program to perform case insensitive string comparison

const string1 = 'JavaScript Program';
const string2 = 'javascript program';

// create regex
let pattern = new RegExp(string1, "gi");

// compare the stings
let result = pattern.test(string2)

if(result) {
    console.log('The strings are similar.');
} else {
    console.log('The strings are not similar.');
}

Output

The strings are similar.

In the above program, the RegEx is used with the test() method to perform case insensitive string comparison.


Example 3: Using localeCompare()

// program to perform case insensitive string comparison

const string1 = 'JavaScript Program';
const string2 = 'javascript program';

let result = string1.localeCompare(string2, undefined, { sensitivity: 'base' });

if(result == 0) {
    console.log('The strings are similar.');
} else {
    console.log('The strings are not similar.');
}

Output

The strings are similar.

In the above program, the localeCompare() method is used to perform case insensitive string comparison.

The localeCompare() method returns a number that indicates whether a reference string comes before, or after, or is the same as the given string.

Here, { sensitivity: 'base' } treats A and a as the same.