Verify whether the initial character of a string is an alphabet letter using JavaScript

Question

Verify whether the initial character of a string is an alphabet letter using JavaScript

I'm currently working on a function to check for specific conditions in a string. However, I've hit a roadblock while attempting to determine whether the first character in the string consists of only letters.

function CheckStringConditions(inputString) { 

// implementation here
let onlyLettersRegex = /^[a-zA-Z]+$/;

if (inputString.length > 4 && inputString.length < 25){
  if (onlyLettersRegex.test(inputString)){
    return true;
  } else {
    return false;
  }
} else {
  return false;
}
}

The string "u__adced_123" should return true but is currently returning false. I even attempted using str[0]==onlyLetters but encountered the same issue.

javascript string

Answer 1

Answer №1

onlyLetters.test(str) examines the entire string. If you want to access the first character, use str.charAt(0).

function CheckFirstLetter(str) {
  let onlyLetters = /^[a-zA-Z]+$/;
  if (str.length > 4 && str.length < 25) {
    if (onlyLetters.test(str.charAt(0))) {
      return true;
    } else {
      return false;
    }
  } else {
    return false;
  }
}
console.log(CheckFirstLetter('Hello World!'));
console.log(CheckFirstLetter('!dlroW olleH'));
console.log(CheckFirstLetter('u__adced_123'));

Answer 2

onlyLetters.test(str) examines the entire string. If you want to access the first character, use str.charAt(0).

function CheckFirstLetter(str) {
  let onlyLetters = /^[a-zA-Z]+$/;
  if (str.length > 4 && str.length < 25) {
    if (onlyLetters.test(str.charAt(0))) {
      return true;
    } else {
      return false;
    }
  } else {
    return false;
  }
}
console.log(CheckFirstLetter('Hello World!'));
console.log(CheckFirstLetter('!dlroW olleH'));
console.log(CheckFirstLetter('u__adced_123'));

Answer 3

Answer №2

const CharacterChecker = str => (
  !!str[4] &&             // > 4
  !str[24] &&             // < 25
  (/^[a-z]+$/i).test(str) // alpha
);

// Examples...

// true: Greater than four characters
console.log(CharacterChecker('Fiver'));

// true: Less than twenty-five characters
console.log(CharacterChecker('TwentyFouroooooooooooooo'));

// false: Twenty-five or more characters
console.log(CharacterChecker('TwentyFiveooooooooooooooo'));

// false: Contains numbers
console.log(CharacterChecker('abcd1234'));

// false: Less than five characters
console.log(CharacterChecker('Four'));

Answer 4

const CharacterChecker = str => (
  !!str[4] &&             // > 4
  !str[24] &&             // < 25
  (/^[a-z]+$/i).test(str) // alpha
);

// Examples...

// true: Greater than four characters
console.log(CharacterChecker('Fiver'));

// true: Less than twenty-five characters
console.log(CharacterChecker('TwentyFouroooooooooooooo'));

// false: Twenty-five or more characters
console.log(CharacterChecker('TwentyFiveooooooooooooooo'));

// false: Contains numbers
console.log(CharacterChecker('abcd1234'));

// false: Less than five characters
console.log(CharacterChecker('Four'));

Verify whether the initial character of a string is an alphabet letter using JavaScript

Answer №1

Answer №2

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