If a local variable or a local function is declared but not used, it is dead code and should be removed. Doing so will improve maintainability because developers will not wonder what the variable or function is used for.

Noncompliant Code Example

function numberOfMinutes(hours) {
  var seconds = 0;   // seconds is never used
  return hours * 60;
}

Compliant Solution

function numberOfMinutes(hours) {
  return hours * 60;
}