Main difference between map and reduce

Question

I used both methods but I am quite confused regarding the usage of both methods.

Is anything that map can do but reduce can not and vice ve

Answer 1

Let's take a look of these two one by one.

Map

Map takes a callback and run it against every element on the array but what's makes it unique is it generate a new array based on your existing array.

var arr = [1, 2, 3];

var mapped = arr.map(function(elem) {
    return elem * 10;
})

console.log(mapped); // it genrate new array

Reduce

Reduce method of the array object is used to reduce the array to one single value.

var arr = [1, 2, 3];

var sum = arr.reduce(function(sum, elem){
    return sum + elem;
})

console.log(sum) // reduce the array to one single value