how does foreach work in javascript code example

Example 1: javascript foreach

var colors = ['red', 'blue', 'green'];

colors.forEach(function(color) {
  console.log(color);
});

Example 2: javascript foreach

let numbers = ['one', 'two', 'three', 'four'];

numbers.forEach((num) => {
  console.log(num);
});  // one   //two //three // four

Example 3: forEach

const arraySparse = [1,3,,7]
let numCallbackRuns = 0

arraySparse.forEach((element) => {
  console.log(element)
  numCallbackRuns++
})

console.log("numCallbackRuns: ", numCallbackRuns)

// 1
// 3
// 7
// numCallbackRuns: 3
// comment: as you can see the missing value between 3 and 7 didn't invoke callback function.

Example 4: javascript foreach syntax

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

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