javascript - 如何计算JavaScript数组中变量重复的次数？

Question

如何获取数组成员及其重复次数(重复)？

我目前有这个脚本

//COUNT VAL
var curr = '';
var previous = '';
var arr = new Array();
var sorted = count.sort();
for(var c=0; c < sorted.length; c++){
if(sorted[c] != ''){
if(sorted[c] != curr){
var repeat = 1;
arr[sorted[c]] = repeat;
curr = sorted[c];
}
else if(sorted[c] == curr){
repeat++;
}
}
}
alert(JSON.stringify(arr));

数组“count”的值为(我使用 JSON.stringify):

[" 2"," 2"," 2","1","1","1","1","1","1","1","1","1","1",null,null,null,null,null,null,null,null,null,null,null,null,null]

我期望我的脚本显示什么...(我期望它返回一个数组)

[1: 10, 2: 3]

(x: y) x 是数字，y 是重复次数。

我得到了什么...

[null,1,1]

Answer 1

var a = [" 2"," 2"," 2","1","1","1","1","1","1","1","1","1","1",null,null,null,null,null,null,null,null,null,null,null,null,null];

var counts = a.reduce( function(obj, cur){
    if( !obj[cur] ) {
        obj[cur] = 0;
    }
    obj[cur]++;
    return obj;
}, {});

结果

2: 3
1: 10
null: 13