remove non similar values from an array of objects based on another array

Question

I have 2 arrays and I would like to compare them and remove from the first arr 50% of the different values from the guide arr.

const arrToManipulate = [
    {val: 'a', vis: true}, {val: 'b', vis: true}, {val: 'c', vis: true}, {val: 'd', vis: true}
];
const guideArr = ['a','b'];

my expected result should be:

const finalArr = [
    {val: 'a', vis: true}, {val: 'b', vis: true}, {val: 'd', vis: true}
];

in my case it doesnt matter if value c or value d will remain, as long as only 50% of the different values will removed.

so far I tried to get a log of all the non-similar value but no success so far - but I get the same values twice of twice or not correct vlues.

for (let i = 0; i < arrToManipulate .length; i++) {
            for ( let j = 0; j < guideArr .length; j++) {
                if (arrToManipulate [i].val !== guideArr [j]) {
                    console.log(arrToManipulate[i].val)
                }
            }
        }

Answer 1

Iterate the array you want to extract the matching values and half of the non-matching values. If the element is in the guide array add it. Otherwise add it 50%.

function cutDifferentValues(arrToManipulate, guideArr){
    var j = 0;
    var result = [];

    for (var i = 0; i < arrToManipulate.length; i++){
        if (guideArr.includes(arrToManipulate[i].val)){
            result.push(arrToManipulate[i]);
            continue;
        }
        else if (j % 2 == 0){
            result.push(arrToManipulate[i]);
        }
        j++;
    }
    return result;
}