A dead store happens when a local variable is assigned a value that is not read by any subsequent instruction or when an object property is assigned a value that is not subsequently used. Calculating or retrieving a value only to then overwrite it or throw it away, could indicate a serious error in the code. Even if it's not an error, it is at best a waste of resources. Therefore all calculated values should be used.

Noncompliant Code Example

function pow(a: number, b: number) {
  if(b == 0) {
    return 0;
  }
  let x = a;
  for(let i = 1; i < b; i++) {
    x = a * i;  //Dead store because the last return statement should return x instead of returning a
  }
  return a;
}

Compliant Solution

function pow(a: number, b: number) {
  if(b == 0) {
    return 0;
  }
  let x = a;
  for(let i = 1; i < b; i++) {
    x = a * i;
  }
  return x;
}

Exceptions

This rule ignores initializations to -1, 0, 1, null, true, false, "", [] and {}.

See