Split string into groups - JavaScript

Given a string that consists of alphabets, numbers, and special characters, we need to split it into three separate strings based on character type.

We'll create three strings where:

• S1 contains all alphabets from the original string
• S2 contains all numbers from the original string
• S3 contains all special characters from the original string

The characters in each resulting string maintain the same order as they appear in the input string.

Example Implementation

const str = "Th!s String C0nt@1ns d1fferent ch@ract5rs";

const seperateCharacters = str => {
   const strArr = str.split("");
   return strArr.reduce((acc, val) => {
      let { numbers, alpha, special } = acc;
      if(+val){
         numbers += val;
      }else if(val.toUpperCase() !== val.toLowerCase()){
         alpha += val;
      }else{
         special += val;
      };
      return { numbers, alpha, special };
   }, {
      numbers: '',
      alpha: '',
      special: ''
   });
};

console.log(seperateCharacters(str));

{
   numbers: '0115',
   alpha: 'ThsStringCntnsdfferentchractrs',
   special: '! @  @'
}

How It Works

The function uses these detection methods:

• Numbers: Uses +val to check if the character converts to a truthy number
• Alphabets: Compares toUpperCase() and toLowerCase() - alphabets will differ, non-alphabets won't
• Special characters: Everything else (spaces, punctuation, symbols)

Alternative Approach Using Regular Expressions

const str = "Th!s String C0nt@1ns d1fferent ch@ract5rs";

const separateWithRegex = str => {
   return {
      alpha: str.replace(/[^a-zA-Z]/g, ''),
      numbers: str.replace(/[^0-9]/g, ''),
      special: str.replace(/[a-zA-Z0-9]/g, '')
   };
};

console.log(separateWithRegex(str));

{
   alpha: 'ThsStringCntnsdfferentchractrs',
   numbers: '0115',
   special: '! @  @'
}

Comparison

Conclusion

Both approaches effectively separate strings by character type while preserving order. The regex method is more concise and readable for simple character classification tasks.