javascript(函數式編程思考) ---> Map-Filter

標籤：length   res   []   數組   class   處理   函數式   ...   console   

let add = x=>x+1;//Map :: (a -> b) -> [a] -> [b]let Map = (function(result,f,arr){    //閉包儲存累積對象    let result = [];    return function map(f,arr){            if(!Array.isArray(arr)){                return "要處理的對象為數組";            }            if(arr.length ==0){                return [];            }else{                let [head,...tail] = arr;                result.push(f(head));                // 通過回調map遍曆目標對象arr,f處理過的元素存入result,tail為[]即遍曆結束,可以返回result                return tail.length == 0 ? result : map(f,tail);            }    }})();let test = Map(add,[1,2,3]);console.log(test);//[2,3,4]

 

 

let biggerTen = x => x>10;
//Filter :: (a -> Bool) -> [a] -> [a]let Filter = (function(){    let result=[];    return function filter(f,arr){            if(!Array.isArray(arr)){                return "要處理的對象為數組";            }            if(arr.length == 0){                return [];            }else{                let [head,...tail] = arr;                f(head) && result.push(head);                return tail.length == 0 ? result : filter(f,tail);            }    };})();let testFilter = Filter(biggerTen,[1,5,10,44,12,2,5]);console.log(testFilter);//[44,12]

 

　　

javascript(函數式編程思考) ---> Map-Filter