Check out example codes for "array objects to array of one property". It will help you in understanding the concepts better.

Code Example 1

//Getting One Value from an Array of Items or sum of array
var numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
var total = numbers.reduce(function(total, current) {
    return total + current;
}, 0);

console.log(total);

Code Example 2

let result = objArray.map(a => a.foo);

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