for-loops.js

for (var i = 0; i < 10; i++) {
  document.write(i + ": " + i*3 + "<br />");
}
var sum = 0;
for (var i = 0; i < a.length; i++) {
  sum + = a[i];
}               // parsing an array
html = "";
for (var i of custOrder) {
  html += "<li>" + i + "</li>";
}