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Require Brace Style (brace-style)

Brace style is closely related to indent style in programming and describes the placement of braces relative to their control statement and body. There are probably a dozen, if not more, brace styles in the world.

The one true brace style is one of the most common brace styles in JavaScript, in which the opening brace of a block is placed on the same line as its corresponding statement or declaration. For example:

if (foo) {
  bar();
} else {
  baz();
}

One common variant of one true brace style is called Stroustrup, in which the else statements in an if-else construct, as well as catch and finally, must be on its own line after the preceding closing brace. For example:

if (foo) {
  bar();
}
else {
  baz();
}

Another style is called Allman, in which all the braces are expected to be on their own lines without any extra indentation. For example:

if (foo)
{
  bar();
}
else
{
  baz();
}

While no style is considered better than the other, most developers agree that having a consistent style throughout a project is important for its long-term maintainability.

Rule Details

This rule enforces consistent brace style for blocks.

Options

This rule has a string option:

  • "1tbs" (default) enforces one true brace style
  • "stroustrup" enforces Stroustrup style
  • "allman" enforces Allman style

This rule has an object option for an exception:

  • "allowSingleLine": true (default false) allows the opening and closing braces for a block to be on the same line

1tbs

Examples of incorrect code for this rule with the default "1tbs" option:

/*eslint brace-style: "error"*/

function foo()
{
  return true;
}

if (foo)
{
  bar();
}

try
{
  somethingRisky();
} catch(e)
{
  handleError();
}

if (foo) {
  bar();
}
else {
  baz();
}

Examples of correct code for this rule with the default "1tbs" option:

/*eslint brace-style: "error"*/

function foo() {
  return true;
}

if (foo) {
  bar();
}

if (foo) {
  bar();
} else {
  baz();
}

try {
  somethingRisky();
} catch(e) {
  handleError();
}

// when there are no braces, there are no problems
if (foo) bar();
else if (baz) boom();

Examples of correct code for this rule with the "1tbs", { "allowSingleLine": true } options:

/*eslint brace-style: ["error", "1tbs", { "allowSingleLine": true }]*/

function nop() { return; }

if (foo) { bar(); }

if (foo) { bar(); } else { baz(); }

try { somethingRisky(); } catch(e) { handleError(); }

stroustrup

Examples of incorrect code for this rule with the "stroustrup" option:

/*eslint brace-style: ["error", "stroustrup"]*/

function foo()
{
  return true;
}

if (foo)
{
  bar();
}

try
{
  somethingRisky();
} catch(e)
{
  handleError();
}

if (foo) {
  bar();
} else {
  baz();
}

Examples of correct code for this rule with the "stroustrup" option:

/*eslint brace-style: ["error", "stroustrup"]*/

function foo() {
  return true;
}

if (foo) {
  bar();
}

if (foo) {
  bar();
}
else {
  baz();
}

try {
  somethingRisky();
}
catch(e) {
  handleError();
}

// when there are no braces, there are no problems
if (foo) bar();
else if (baz) boom();

Examples of correct code for this rule with the "stroustrup", { "allowSingleLine": true } options:

/*eslint brace-style: ["error", "stroustrup", { "allowSingleLine": true }]*/

function nop() { return; }

if (foo) { bar(); }

if (foo) { bar(); }
else { baz(); }

try { somethingRisky(); }
catch(e) { handleError(); }

allman

Examples of incorrect code for this rule with the "allman" option:

/*eslint brace-style: ["error", "allman"]*/

function foo() {
  return true;
}

if (foo)
{
  bar(); }

try
{
  somethingRisky();
} catch(e)
{
  handleError();
}

if (foo) {
  bar();
} else {
  baz();
}

Examples of correct code for this rule with the "allman" option:

/*eslint brace-style: ["error", "allman"]*/

function foo()
{
  return true;
}

if (foo)
{
  bar();
}

if (foo)
{
  bar();
}
else
{
  baz();
}

try
{
  somethingRisky();
}
catch(e)
{
  handleError();
}

// when there are no braces, there are no problems
if (foo) bar();
else if (baz) boom();

Examples of correct code for this rule with the "allman", { "allowSingleLine": true } options:

/*eslint brace-style: ["error", "allman", { "allowSingleLine": true }]*/

function nop() { return; }

if (foo) { bar(); }

if (foo) { bar(); }
else { baz(); }

try { somethingRisky(); }
catch(e) { handleError(); }

When Not To Use It

If you don't want to enforce a particular brace style, don't enable this rule.

Further Reading