how does foreach loop work in js code example

Example 1: javascript foreach

const avengers = ['thor', 'captain america', 'hulk'];
avengers.forEach((item, index)=>{
	console.log(index, item)
})

Example 2: javascript foreach syntax

const marks = [12, 17, 14];
let sum = 0;

marks.forEach(mark => {
  sum += mark;
});