js如何判断相同的元素个数

function countOccurrences(arr, val) {
    return arr.filter(x => x === val).length;
}

const array = [1, 2, 3, 4, 2, 2, 3];
console.log(countOccurrences(array, 2)); // 输出：3

function countOccurrences(arr, val) {
    return arr.reduce((a, v) => (v === val ? a + 1 : a), 0);
}

const array = [1, 2, 3, 4, 2, 2, 3];
console.log(countOccurrences(array, 2)); // 输出：3

function countOccurrences(arr) {
    const counts = {};
    arr.forEach(x => counts[x] = (counts[x] || 0) + 1);
    return counts;
}

const array = [1, 2, 3, 4, 2, 2, 3];
console.log(countOccurrences(array)); // 输出：{ '1': 1, '2': 3, '3': 2, '4': 1 }

function deepEqual(obj1, obj2) {
    return JSON.stringify(obj1) === JSON.stringify(obj2);
}

function countOccurrences(arr, val) {
    return arr.filter(x => deepEqual(x, val)).length;
}