Divide a string into n equal parts - JavaScript

We are required to write a JavaScript function that takes in a string and a number n (such that n exactly divides the length of string). We need to return an array of string of length n containing n equal parts of the string.

Let's write the code for this function ?

Example

const str = 'this is a sample string';
const num = 5;
const divideEqual = (str, num) => {
    const len = str.length / num;
    const creds = str.split("").reduce((acc, val) => {
        let { res, currInd } = acc;
        if(!res[currInd] || res[currInd].length < len){
            res[currInd] = (res[currInd] || "") + val;
        }else{
            res[++currInd] = val;
        };
        return { res, currInd };
    }, {
        res: [],
        currInd: 0
    });
    return creds.res;
};
console.log(divideEqual(str, num));

Output

Following is the output in the console ?

[ 'this ', 'is a ', 'sampl', 'e str', 'ing' ]

Simpler Approach Using Substring

Here's a more straightforward solution using the substring() method:

const divideEqualSimple = (str, num) => {
    const partLength = str.length / num;
    const result = [];
    
    for (let i = 0; i < num; i++) {
        const start = i * partLength;
        const end = start + partLength;
        result.push(str.substring(start, end));
    }
    
    return result;
};

const str = 'this is a sample string';
const num = 5;
console.log(divideEqualSimple(str, num));

[ 'this ', 'is a ', 'sampl', 'e str', 'ing' ]

How It Works

Both approaches divide the string length by the number of parts to get the length of each part. The first method uses reduce() to build the array character by character, while the second uses substring() to extract parts directly based on calculated positions.

Conclusion

The substring approach is more readable and efficient for dividing strings into equal parts. Both methods work correctly when the string length is exactly divisible by n.