How Can You Use `string.startsWith()` Method While Ignoring Case in JavaScript?

How to use `string.startsWith()` method ignoring the case?

const str = 'Session'; const prefix = 'sEsSi';

In JavaScript, the `string.startsWith()` method checks if a particular string starts with a specified prefix. However, this method is case-sensitive, meaning that 'Session' will not match with 'sEsSi'. To perform a case-insensitive comparison, you must convert both the string and the prefix to the same case before making the comparison.

function startsWithIgnoreCase(str, prefix) {
    return str.toLowerCase().startsWith(prefix.toLowerCase());
}

// Example Usage
const str = 'Session';
console.log(startsWithIgnoreCase(str, 'sEsSi')); // Outputs: true

Causes

• The `string.startsWith()` method is inherently case-sensitive.
• Directly comparing the original string with the prefix will yield false results due to differing character cases.

Solutions

• Convert both the source string and the prefix to lower case (or upper case) using `toLowerCase()` or `toUpperCase()` methods before using `startsWith()`.
• Example implementation: Create a function that checks for starts with a case-insensitive match.

Mistake: Forgetting to convert both strings to the same case before comparison.

Solution: Always convert both the target string and the prefix using `toLowerCase()` or `toUpperCase()`.

Mistake: Using `string.startsWith()` directly without case conversion thinking it will handle case insensitivity.

Solution: Understand that `startsWith()` is case-sensitive, and you need to implement a custom case-insensitive check.