for element in array to create a map code example

Example 1: use map to loop through an array

let squares = [1,2,3,4].map(function (val) {  
    return val * val;  
}); 
// squares will be equal to [1, 4, 9, 16]

Example 2: map a property from array of objects javascript

var result = objArray.map(function(a) {return a.foo;});