SOURCE

function maxPoints(points){
    if(points.length <2) return points.length;
    let maxCount = 0;
    for(let i =0;i<points.length;i++){
        const slopes = new Map();
        let samePointCount = 1;

        for(let j =i+1;j<points.length;j++){
            if(points[i][0]===points[j][0] &&points[i][1]===points[j][1]){
                samePointCount++
                continue
            }
            const dy = points[j][1] - points[i][1];
            const dx = points[j][0] - points[i][0];

            const gcd = getGCD(dy,dx);
            const slope = `${dy/gcd}/${dx/gcd}`
            slopes.set(slope,(slopes.get(slope) ||0)+1);
        }
        let currentMax= 0;
        for(let count of slopes.values()){
            currentMax = Math.max(currentMax,count)
        }
        maxCount = Math.max(maxCount,currentMax+samePointCount)
    }
    return maxCount
}

function getGCD(a,b) {
    if(b===0) return a;
    return getGCD(b,a%b)
}

const points = [[1,1],[2,2],[3,3],[3,2],[4,1],[5,1]]
console.log(maxPoints(points))