javascript 获取一个数组中重复的元素及个数

2018-08-04 javascript 获取一个数组中重复的元素及个数

  function getRepeatNum(ary){
    var list = [];
    var listMap = {};
    for (var i = 0, len = ary.length; i < len; i++) {
        
        key = ary[i]; // key为不重复的元素，值为number
        if (!!listMap[key]) {
            listMap[key]++;
        } else {
            listMap[key] = 1;
        }
    }
    for (var item in listMap) {
        list.push({
            value: item,
            number: listMap[item]
        })
    }
    return list
 }