【持续更新】前端面试代码题

让我纸上手写我确实写不出啊。。。。

挺无语的一题：

      // "aabbbbaaacccdd" 按照 字母的出现次数从大到小排序，最终结果为['a','b','c','d'] 
        let str = "bbbbaaddaaaccc"   // -> ['a','b','c'] 
        function getCount(){
            let jsonObj = {}  // {a:5,b:4,c:3} 
            for(let i in str){  
                if(jsonObj[str[i]] == undefined){
                    jsonObj[str[i]] = 1
                }else{
                    jsonObj[str[i]] = jsonObj[str[i]] + 1
                }   
            }
            return jsonObj
        }  
        function mySort(obj){
            let arr = [] 
            let countKeys = Object.keys(obj) // ['a','b','c','d']
            for(let i = 0; i<countKeys.length-1;i++){ 
                for(let j = 0;j<countKeys.length-1-i;j++){
                    if(obj[countKeys[j]] < obj[countKeys[j + 1]]){
                        let temp = countKeys[j];
                        countKeys[j] = countKeys[j+1]
                        countKeys[j+1] = temp
                    } 
                }
            }
            return countKeys 
        }
        console.log(mySort(getCount()));
        
       

深克隆：

 // 类型检查
        function getType(obj){
            return Object.prototype.toString.bind(obj)().slice(8,-1)
        }


        function deepClone(obj){
            let result;
            switch(getType(obj)){
                case 'Object':{
                    result = {}
                    break;
                }
                case 'Array':{
                    result = []
                    break;
                }
                default:{
                    result = obj;
                }
            } 
            for(let key in obj){
                if(result == 'Object' || result == 'Array'){
                    deepClone(obj[key])
                }else{ 
                    result[key] = obj[key]
                }
            }
            return result;
        }
       console.log(deepClone({name:123,arr:[1,2,3,4]}));

数组去重复：

 let arr1 = [1,1,2,2,4,4,3,3]
        let arr2 = []
        function foo(arr1){
            for(let i in arr1){
                if(arr2.indexOf(arr1[i]) === -1){
                    arr2.push(arr1[i])
                }
            }
        }
        foo(arr1)
        console.log(arr2);