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[js][填坑] 数组中各元素的数量、数量最多的元素

#遍历关联数组、对象，用 for in

            function eleCount(arr) {
//                if (typeof arr == 'string') {
//                    arr = arr.split('');
//                }不需要
                var temp = {};
                var maxName;
                var maxCount = 0;
                for (var i = 0; i < arr.length; i++) {
                    if (temp[arr[i]]) {
                        temp[arr[i]] += 1;
                    } else {
                        temp[arr[i]] = 1;
                    }
                }
                console.info(temp);
                for (var k in temp) {
                    if (maxName) {
                        if (maxCount < temp[k]) {
                            maxName = k;
                            maxCount = temp[k];
                        }
                    } else {
                        maxName = k;
                        maxCount = temp[k];
                    }
                }
                console.warn(maxName, maxCount);
            }
            var arr1 = [4, 5, 4, 7, 8, 4, 2, 67, 5, 89, 5, 67];
            var arr2 = ['a', 'b', 'd', 'e', 'f', 'h', 'g', 'k', 'a', 'b', 'e', 'd'];
            var arr3 = ['a', 'b', 'd', 'e', 'F', 'F', 'g', 'k', 'A', 'B', 'e', 'd'];
            var arr4 = 'sdfxcaweasdazkvda';
            eleCount(arr1);
            eleCount(arr2);
            eleCount(arr3);
            eleCount(arr4);
            //只对数字数组有效,对关联数组无效
            console.log(Math.max.apply(null, arr1)); //89
            console.log(Math.max.apply(null, arr2)); //NaN
            console.log(Math.max.apply(null, arr3)); //NaN

 

 

#abandon

<!DOCTYPE html>
<html>

    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>

    <body>
        <script>
            var a = [4, 5, 4, 7, 8, 4, 2, 67, 5, 89, 5, 67];
            //var b = a.sort();//浅复制
            var b = [];
            //深复制防止改变原数组
            //深复制方法一
            //            b = a.map(function(e, i, arr) {
            //                return e;
            //            })            
            //深复制方法二
            //            a.forEach(function(e, i, arr) {
            //                b[i] = e;
            //            });
            //深复制方法三
            for (var i = 0; i < a.length; i++) {
                b[i] = a[i];
            }
            b.sort();
            var count = 1;
            var temp = [];
            var max = 1;
            var maxname;
            for (var i = 0; i < b.length; i++) {
                if (b[i] == b[i + 1]) {
                    count++;
                } else {
                    if (max < count) {
                        max = count;
                        maxname = b[i];
                    }
                    console.log(b[i] + '的个数为：' + count);
                    
                    count = 1;
                }
            }
            console.log(a);
            console.log(b);
            console.log(maxname + '的个数最多，为：' + max);
        </script>
    </body>

</html>

 

posted @ 2016-02-26 14:06  晴明桑  阅读(495)  评论(0)    收藏  举报