4. 함수형 프로그래밍 - each

const users = [

{ isView : false, id : 1, name : "A", age : 36 },

{ isView : true, id : 2, name : "B", age : 32 },

{ isView : true, id : 3, name : "C", age : 31 },

{ isView : false, id : 4, name : "D", age : 27 },

{ isView : true, id : 5, name : "E", age : 25 },

{ isView : false, id : 6, name : "F", age : 31 }

];

function filter( $list, fn ){

let nList = [];

each( $list, ( $item ) => {

if( fn( $item )) nList.push( $item );

})

return nList;

}

function map( $list, fn ){

let nList = [];

each( $list, ( $item ) => nList.push( fn( $item )));

return nList;

}

function each( $list, fn ){

var item;

for( item of $list ){

fn( item );

}

}

let age = map(

filter( users, ( item ) => item.isView ),

( item ) => item.age );

let name = map(

filter( users, ( item ) => item.isView ),

( item ) => item.name );

let id = map(

filter( users, ( item ) => item.age >= 30 ),

( item ) => item.id );

console.log( age, name, id );