How to Check Case of Letter in JavaScript ?

JavaScript - Validate Password in JS

Last Updated : 16 Jan, 2025

To validate a password in JavaScript regex to ensure it meets common requirements like length, uppercase letters, lowercase letters, numbers, and special characters. we will validate a strong or weak password with a custom-defined range.

JavaScript

let regex = /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@.#$!%*?&])[A-Za-z\d@.#$!%*?&]{8,15}$/;
let s1 = "Geeks@123";
let s2 = "GeeksforGeeks";
let s3 = "Geeks123";
console.log(s1, regex.test(s1));
console.log(s2, regex.test(s2));
//Driver Code Starts
console.log(s3, regex.test(s3));
//Driver Code Ends

Output

Geeks@123 true
GeeksforGeeks false
Geeks123 false

Regula Expression Breakdown:

^(?=.*[a-z]): Ensures at least one lowercase letter.
(?=.*[A-Z]): Ensures at least one uppercase letter.
(?=.*\d): Ensures at least one digit.
(?=.*[@$!%*?&]): Ensures at least one special character.
[A-Za-z\d@$!%*?&]{8,}$: Ensures the password is at least 8 characters long.

Multiple Output based on Password Strength

In this method, we will set the password strength on the basis of the number of combinations for numbers, letters, special symbols, etc.

JavaScript

//Driver Code Starts
const levels = {
    1: "Very Weak",
    2: "Weak",
    3: "Medium",
    4: "Strong",
};

//Driver Code Ends
function checkPwd(pwd) {
    if (pwd.length > 15) {
        return console.log(pwd + " - Too lengthy");
    } else if (pwd.length < 8) {
        return console.log(pwd + " - Too short");
    }

    const checks = [
        /[a-z]/,     // Lowercase
        /[A-Z]/,     // Uppercase
        /\d/,        // Digit
        /[@.#$!%^&*.?]/ // Special character
    ];
    let score = checks.reduce((acc, rgx) => acc + rgx.test(pwd), 0);

    console.log(pwd + " - " + levels[score]);
}
//Driver Code Starts

let pwds = [
    "u4thdkslfheogica",
    "G!2ks",
    "GeeksforGeeks",
    "Geeks123",
    "GEEKS123",
    "Geeks@123#",
];

pwds.forEach(checkPwd);
//Driver Code Ends

Output

u4thdkslfheogica - Too lengthy
G!2ks - Too short
GeeksforGeeks - Weak
Geeks123 - Medium
GEEKS123 - Weak
Geeks@123# - Strong

How to Check Case of Letter in JavaScript ?

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