JavaScript - String Contains Only Alphabetic Characters or Not

Here are several methods to check if a string contains only alphabetic characters in JavaScript

Using Regular Expression (/^[A-Za-z]+$/) - Most USed

The most common approach is to use a regular expression to match only alphabetic characters (both uppercase and lowercase).

let s = "HelloWorld";
let isAlphabetic = /^[A-Za-z]+$/.test(s);
console.log(isAlphabetic);

Output

true

This checks if the string contains only the letters A-Z and a-z. It will return true if all characters are alphabetic and false otherwise.

Using every() Method with Regular Expression

The every() method can be used with a regular expression to iterate over each character and verify it matches [A-Za-z].

let s = "HelloWorld";
let isAlphabetic = Array.from(s).every((char) =>
    /[A-Za-z]/.test(char));
console.log(isAlphabetic);

Output

true

This approach works well for checking each character individually against the pattern.

Using for Loop with charCodeAt()

Using a for loop, you can check each character for alphabets without regular expressions.

let s = "HelloWorld";
let isAlphabetic = true;

for (let i = 0; i < s.length; i++) {
    let code = s.charCodeAt(i);
    if (!(code >= 65 && code <= 90) && !(code >= 97 && code <= 122)) {
        isAlphabetic = false;
        break;
    }
}
console.log(isAlphabetic);

Output

true

Using every() with charCodeAt()

This method uses Array.from() to split the string into characters, then checks each one’s ASCII code.

let s = "HelloWorld";
let isAlphabetic = Array.from(s).every(char => {
    let code = char.charCodeAt(0);
    return (code >= 65 && code <= 90) || (code >= 97 && code <= 122);
});
console.log(isAlphabetic); 

Output

true

Using isNaN() Function

To check if each character is non-numeric, you can use isNaN() along with checking for alphabetic ranges.

let s = "HelloWorld";
let isAlphabetic = Array.from(s).every(
    (char) => isNaN(char) && /[A-Za-z]/.test(char)
);
console.log(isAlphabetic);

Output

true

Using filter() with match()

The filter() method can filter out non-alphabetic characters by checking each one with match(), and the length of the result should match the original string length if all are alphabetic.

let s = "HelloWorld";
let isAlphabetic =
    s.split("").filter((char) =>
         char.match(/[A-Za-z]/)).length === s.length;
console.log(isAlphabetic);

Output

true

The regular expression (/^[A-Za-z]+$/) remains the most efficient approach. However, methods like every() with charCodeAt() or a for loop offer flexibility for character-by-character validation.