Defining a function inside of a loop can yield unexpected results. Such a function keeps references to the variables which are defined in outer scopes. All function instances created inside the loop therefore see the same values for these variables, which is probably not expected.

Noncompliant Code Example

var funs = [];
for (var i = 0; i < 13; i++) {
  funs[i] = function() { // Non-Compliant
    return i;
  };
}
console.log(funs[0]()); // 13 instead of 0
console.log(funs[1]()); // 13 instead of 1
console.log(funs[2]()); // 13 instead of 2
console.log(funs[3]()); // 13 instead of 3
...