Цикли

for (i=0; i<10; i++) {

}

while (a < 10) {

}

do {

} while (a < 10);

break

continue

let mas = [10, 20, 30];

for (let value of mas) {

    console.log(value)

}

var person = {fname:"Майстер", lname:"Йодо", age:125}; 

var x;

for (x in person) {

txt += person[x] + " ";

}

var i;

var l = arr.length;  // краще

for (i = 0; i < l; i++) {

}