JavaScript获取字符串中出现次数最多的元素和出现次数

var str = 'adffkdgskdaada';
function test (data) {
    // obj = 每个元素以及出现次数，count = 最多出现次数，maxStr = 最多出现的元素
    let obj = {},count = 0,maxStr = []; 
    for (let i = 0; i < data.length; i++) {
        if (obj[data[i]]) {
            obj[data[i]]++;    
        } else {
            obj[data[i]] = 1;
        }
    }
    for (let item in obj) {
        if (obj[item] > count) {
            maxStr = [item];
            count = obj[item];
        } else if (obj[item] == count) {
             maxStr.push(item);
        }
    }
    return `出现最多的是${maxStr.join(',')}，出现次数为${count}`;
}