for loop in javascript explained code example

Example 1: javascript loop through array

var colors = ["red","blue","green"];
colors.forEach(function(color) {
  console.log(color);
});

Example 2: for in loop javascript

function diagonalDifference(arr) {
    // Write your code here
    // return (arr); 11,2,4,4,5,6,10,8,-12
    let n = arr.length;
    let pri,sec = 0;

    pri = sec = 0; //initialize both diagonal sum to 0
    for (let i= 0; i < n; i++) {
        //console.log( "PRI(arr)= ", i,i);
        //console.log( arr[i][i]);
        //console.log( "SEC(arr)= ", i,n-i-1);
        //console.log( arr[i][n-i-1]);
        pri += arr[i][i];
        sec += arr[i][n - i - 1]; 
    }
	
  	// return |x| is the absolute value of x
    if(pri==sec){
        return (0);
    }else {
        if (pri>sec){
            return (pri-sec);
        }else{
            return (sec-pri);
        }
    }
}