计算某个值在javascript中出现的次数

function countOccurrences(arr, value) {
    let count = 0;
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] === value) {
            count++;
        }
    }
    return count;
}

// 示例
const array = [1, 2, 3, 2, 4, 2, 5];
console.log(countOccurrences(array, 2)); // 输出：3

function countOccurrences(arr, value) {
    return arr.reduce((count, item) => {
        return item === value ? count + 1 : count;
    }, 0);
}

// 示例
const array = [1, 2, 3, 2, 4, 2, 5];
console.log(countOccurrences(array, 2)); // 输出：3

function countOccurrences(arr, value) {
    return arr.filter(item => item === value).length;
}

// 示例
const array = [1, 2, 3, 2, 4, 2, 5];
console.log(countOccurrences(array, 2)); // 输出：3

function countOccurrences(arr) {
    const map = new Map();
    arr.forEach(item => {
        if (map.has(item)) {
            map.set(item, map.get(item) + 1);
        } else {
            map.set(item, 1);
        }
    });
    return map;
}

// 示例
const array = [1, 2, 3, 2, 4, 2, 5];
const occurrences = countOccurrences(array);
console.log(occurrences.get(2)); // 输出：3