js重复

//统计一个数组中有多少个不重复的单词：
// 不用reduce时： 
var arr = ["apple","orange","apple","orange","pear","orange"]; 
function getWordCnt(){ 
    var obj = {}; 
    for(var i= 0, l = arr.length; i< l; i++){ 
        var item = arr[i]; 
        obj[item] = (obj[item] +1 ) || 1; 
    } 
    return obj; 
}
console.log(getWordCnt());//{apple: 2, orange: 3, pear: 1}
// 用reduce时： 
var arr = ["apple","orange","apple","orange","pear","orange"]; 
function getWordCnt(){ 
    return arr.reduce(function(prev,next){ 
        prev[next] = (prev[next] + 1) || 1; 
        return prev; 
    },{}); 
} 
console.log(getWordCnt());//{apple: 2, orange: 3, pear: 1}