Segregate all 0s on right and 1s on left in JavaScript

We have an array of Numbers that contains 0, 1 and some other numbers. We are required to write a JavaScript function that takes in this array and brings all 1s to the start and 0s to the end

Let's write the code for this function ?

Example

const arr = [3, 2, 1, 8, 9, 0, 1, 9, 0, 2, 1, 0, 2, 0, 1, 0, 1, 1, 4, 0, 3];

const segregate = arr => {
    const copy = arr.slice();
    for(let i = 0; i < copy.length; i++){
        if(copy[i] === 0){
            copy.push(copy.splice(i, 1)[0]);
        }else if(copy[i] === 1){
            copy.unshift(copy.splice(i, 1)[0]);
        };
        continue;
    };
    return copy;
};

console.log(segregate(arr));

Output

The output in the console will be ?

[
    1, 1, 1, 3, 2, 8, 9,
    1, 9, 2, 2, 1, 1, 4,
    3, 0, 0, 0, 0, 0, 0
]

How It Works

The function creates a copy of the original array using slice(). It then iterates through the array:

• When it finds a 0, it removes it using splice() and adds it to the end with push()
• When it finds a 1, it removes it and adds it to the beginning with unshift()
• Other numbers remain in their relative positions

Alternative Approach Using Filter

const segregateWithFilter = arr => {
    const ones = arr.filter(num => num === 1);
    const others = arr.filter(num => num !== 0 && num !== 1);
    const zeros = arr.filter(num => num === 0);
    
    return [...ones, ...others, ...zeros];
};

const testArr = [3, 2, 1, 8, 9, 0, 1, 9, 0, 2, 1, 0];
console.log(segregateWithFilter(testArr));

[1, 1, 1, 3, 2, 8, 9, 9, 2, 0, 0, 0]

Conclusion

Both approaches successfully segregate 0s and 1s while preserving other numbers. The filter method is more readable, while the splice approach modifies the array in-place during iteration.