“去哪儿网”2015春招前端面试题

第一题：给定有序数组，从中找出指定数字下标，如果没找到，返回-1。（记忆中题目描述大概是这样子）

    /*num:待查找的数据*/
         Array.prototype.searchIndex = function(num){
             var result = [];
             for(var i = 0,len = this.length; i < len; i++){
                 if(this[i] == num){
                     result.push(i);
                 }
             }
             if(result.length == 0)
                 result.push(-1);
             return result;
         }

        var arr = [1,2,5,5,5,5,5,6,9];
        console.log(arr.searchIndex(5));//[2,3,4,5,6]
        console.log(arr.searchIndex(0));//[-1]    

第二题：给出一个字符串，遇到数字n，则将前方字母输出n次

样例输入：abc3dd1zz2

样例输出：abcabcabcddzzzz

//注意：数字可能是2位数以上
        function print(str){
            var string = "";
            var _str = "";
            var n = 0;
            for(var i = 0, len = str.length; i < len; i++){
                if(str[i] >= 'a' && str[i] <= 'z'){
                    if(n == 0){
                        _str += str[i];
                    }else{
                        for(var j = 0; j < n; j++){
                            string += _str;
                        }
                        n = 0;
                        _str = str[i];
                    }                    
                }else{
                    n = n * 10 + parseInt(str[i]);
                    if(i == len - 1){
                        for(var j = 0; j < n; j++){
                            string += _str;
                        }
                    }
                }
            }
            return string;
        }
            console.log(print('aa3bb5zz6'));//aaaaaabbbbbbbbbbzzzzzzzzzzzz
            console.log(print('3a5c6e'));//aaaaacccccc
            console.log(print('ad13bc10'));//adadadadadadadadadadadadadbcbcbcbcbcbcbcbcbcbc
            console.log(print('22222'));//空字符串
            console.log(print('aaaaa'));//空字符串

第三题：输出文件名的后缀

样例输入：file.js

样例输出：js

方案一：

        function fileSuffix(filename){
            var point = filename.lastIndexOf('.');
            return filename.substring(point + 1);
        }
            console.log(fileSuffix('file.min.js'));//js

方案二：

        function fileSuffix(filename){
            var point = filename.split('.');
            return point[point.length - 1];
        }
            console.log(fileSuffix('file.min.js'));//js
            console.log(fileSuffix('file.js'));//js

第四题：递归，大致题型如下

样例输入：

        var json = {
                name:'john',
                age:'80',
                child:[{                    
                    name:'sindy',
                    age:'60'
                    child:[{
                        name:'bob',
                        age:'40',
                        child:[{
                            name:'sany',
                            age:'20'
                        }]
                    }]
                },
                {
                    name:'susan',
                    age:'70'
                }]
                
        };

样例输出：

<ol>
    <li>john</li>
    <li>80</li>
    <ol>
        <li>sindy</li>
        <li>60</li>
        <ol>
            <li>bob</li>
            <li>40</li>
            <ol>
                <li>sany</li>
                <li>20</li>
            </ol>
        </ol>
    </ol>
    <ol>
        <li>susan</li>
        <li>70</li>
    </ol>
</ol>

我的答案：

    function getHtml(obj){
                var ol = document.createElement('ol');
                if(obj.name){
                    var li = document.createElement('li');
                    li.innerHTML = obj.name;
                    ol.appendChild(li);
                }
                if(obj.age){
                    var li = document.createElement('li');
                    li.innerHTML = obj.age;
                    ol.appendChild(li);
                }
                if(obj.child){
                    for(var i = 0, len = obj.child.length; i < len; i++){
                        ol.appendChild( getHtml(obj.child[i]) );
                    }                   
                }    
                return ol;
            }
        document.getElementById('ol').innerHTML = '<ol>' + getHtml(json).innerHTML + '</ol>';