no-dupe-else-if.md

Pattern: Duplicate condition in if-else chain

Issue: -

Description

Using identical conditions in an if-else-if chain is likely a mistake since the duplicate branch can never be reached. Unless the conditions have side effects, the repeated condition will evaluate to the same result as its first occurrence.

Examples

Example of incorrect code:

if (a) {
  foo();
} else if (b) {
  bar();
} else if (b) {  // Duplicate condition
  baz();
}

if (n > 10) {
  handleBig();
} else if (n < 5) {
  handleSmall();
} else if (n > 10) {  // Never reached
  handleOther();
}

Example of correct code:

if (a) {
  foo();
} else if (b) {
  bar();
} else if (c) {
  baz();
}

if (n > 10) {
  handleBig();
} else if (n < 5) {
  handleSmall();
} else {
  handleOther();
}