PAC-C006 · bitwise-or-in-condition

Bitwise | or & used instead of || or &&

medium · Correctness

A single | or & converts both operands to 32-bit integers. For booleans the result is accidentally right, but both sides are always evaluated and non-boolean operands produce 0, which silently drops the branch.

Why it matters

a | b evaluates both sides (no short-circuit), so a DNS call on the right-hand side runs even when the left side already decided. The operands are coerced to integers: a string such as shExpMatch(...) | "DIRECT" becomes 0 and the condition is never true. & behaves correspondingly. The typo survives casual testing because true | false is 1, which is truthy.

How to fix

Replace | with || and & with &&.

Examples

Bad

function FindProxyForURL(url, host) {
  if (host == "a.corp.example" | host == "b.corp.example") {
    return "DIRECT";
  }
  return "PROXY proxy.corp.example:8080";
}

Open bad example in checker

Good

function FindProxyForURL(url, host) {
  if (host == "a.corp.example" || host == "b.corp.example") {
    return "DIRECT";
  }
  return "PROXY proxy.corp.example:8080";
}

Open good example in checker

Related rules

Assignment used as a condition PAC-E009