用reduce计算数组中某个项出现的次数

[Kelichao]

// 用reduce时：
    var arr = ["李","李","设","弟","弟","生","生","李"]; 
    function getRepeatNum(){ 
        return arr.reduce(function(prev,next){ 
            prev[next] = (prev[next] + 1) || 1; 
            return prev; 
        },{}); 
    } 
    console.log(getRepeatNum());