Expressing numbers in expanded form - JavaScript

Suppose we are given a number 124 and are required to write a function that takes this number as input and returns its expanded form as a string.

The expanded form of 124 is ?

'100+20+4'

How It Works

The algorithm converts each digit to its place value by multiplying it with the appropriate power of 10, then joins non-zero values with '+' signs.

Example

Following is the code ?

const num = 125;
const expandedForm = num => {
    const numStr = String(num);
    let res = '';
    for(let i = 0; i < numStr.length; i++){
        const placeValue = +(numStr[i]) * Math.pow(10, (numStr.length - 1 - i));
        if(numStr.length - i > 1){
            res += `${placeValue}+`
        }else{
            res += placeValue;
        };
    };
    return res;
};
console.log(expandedForm(num));

Output

Following is the output in the console ?

100+20+5

Improved Version

Here's a cleaner approach that filters out zero values and uses array methods:

const expandedFormImproved = num => {
    return String(num)
        .split('')
        .map((digit, index, arr) => {
            const placeValue = digit * Math.pow(10, arr.length - 1 - index);
            return placeValue;
        })
        .filter(value => value > 0)
        .join('+');
};

console.log(expandedFormImproved(125));
console.log(expandedFormImproved(102)); // Handles zeros
console.log(expandedFormImproved(7));   // Single digit

100+20+5
100+2
7

Comparison

Conclusion

Both approaches work for basic cases, but the improved version handles edge cases like zeros and uses modern JavaScript array methods for cleaner, more readable code.