Compare two Arrays and replace Duplicates with values from a third array

Question

var array1 = [\'a\',\'b\',\'c\',\'d\'];
var array2 = [\'a\',\'v\',\'n\',\'d\',\'i\',\'f\'];

var array3 = [\'1\',\'2\',\'3\',\'4\',\'5\',\'6\'];

Just s

Answer 1

You could use a hash table and check against. If the string is not included in the hash table, a replacement value is set for this element.

var array1 = ['a','b','c','d'],
    array2 = ['d','v','n','a','i','f'],
    array3 = ['1','2','3','4','5','6'],
    hash = Object.create(null);

array1.forEach(function (a) {
    hash[a] = true;
});

array2.forEach(function (a, i, aa) {
    if (hash[a]) {
        aa[i] = array3[i];
    }
});

console.log(array2);

ES6 with Set

var array1 = ['a','b','c','d'],
    array2 = ['d','v','n','a','i','f'],
    array3 = ['1','2','3','4','5','6'];

array2.forEach((hash => (a, i, aa) => {
    if (hash.has(a)) {
        aa[i] = array3[i];
    }
})(new Set(array1)));

console.log(array2);