prefer-early-return.md

Prefer early returns over full-body conditional wrapping in function declarations. (prefer-early-return)

A function whose entire body is nested under a conditional statement adds unnecessary nesting and makes the code harder to read. An early return often makes the block more readable.

Rule Details

The following patterns are considered warnings:

function foo() {
  if (a) {
    b();
    c();
  }
}

The following patterns are not warnings:

function foo() {
  if (!a) { return; }

  b();
  c();
}

function bar() {
  if (a) {
    b();
    c();
  }

  d();
}

function baz() {
  if (a) {
    b();
    c();
  } else {
    d();
  }
}

Options

This plugin takes one option: an object with a integer maximumStatements property. This property specifies the maximum number of statements in the conditional for which a full-function body conditional should be allowed. By default, this value is 1, so the following will not be considered a warning:

function foo() {
  if (a) {
    b();
  }
}

Setting maximumStatements to 0 will cause the above to be a warning. Setting maximumStatements to 2 would cause the following not to be considered a warning:

function foo() {
  if (a) {
    b();
    c();
  }
}

When Not To Use It

If you don't care about conditionals that span the entire body of functions, or dislike early returns, you can safely disable this rule.