问两个数组中相同字符串的数量(JS)

EN

var count = 0;
arr1.forEach(function (elem) {
    if (arr2.indexOf(elem) !== -1) {
        count++;
    }
});

var intersect = function (array) {
    var rest = array.slice.call(arguments, 1);
    return array.filter(function(item) {
        return rest.every(function(other) {
            return other.indexOf(item) >= 0;
        });
    });
}

var dups = intersect([1,2,3],[1,2],[5,8,2]);//[2]
var numofdups = dups.length;