How to use the map and filter of JS

Filter is to satisfy the condition of the left, is the original array of filtering;

Map is the processing of the original array, mapped to a new array of one by one mappings

Simple example:

Let arr = [1, 2, 3, 4]

Let NEWARR = Arr.map (function (item) {//using the Map method

return item * 2;

});

Console.log (NEWARR); [2, 4, 6, 8]

Let arr = [1, 2, 3, 4];

Let NEWARR = Arr.filter (function (item) {//using the filter method

if (item% 2!== 0) {

return item;

}

});
Console.log (NEWARR); [1, 3];

How to use the map and filter of JS