Intro to guard clauses.

guard.md

Guard Clause

What is it?

A guard clause is a line of code that prevents the following block of code from running unless a certain condition is met.

Why use guard clauses?

Guard clauses are preferrable to nested conditionals because they are faster and simpler than nesting conditional statements.

Links

• Replace nested Conditionals with Guard Clauses.
• Anti If Campaign.
• Prefer Guard Clauses over nested Conditionals.
• Refactoring nested Conditionals.

Example

const obj = {
  a: {
    b: 'value of b!'
  }
};

function findPropBOfObject (object) {
  object.a || return;
  return object.a.b;
}

function unguardedFindPropBOfObject (object) {
  if (object.a && object.a.b) {
    return object.a.b;
  } else {
    return;
  }
}