@stylistic/js/

lines-around-comment

Many style guides require empty lines before or after comments. The primary goal of these rules is to make the comments easier to read and improve readability of the code.

Rule Details

This rule requires empty lines before and/or after comments. It can be enabled separately for both block (/*) and line (//) comments. This rule does not apply to comments that appear on the same line as code and does not require empty lines at the beginning or end of a file.

Options

This rule has an object option:

• "beforeBlockComment": true (default) requires an empty line before block comments
• "afterBlockComment": true requires an empty line after block comments
• "beforeLineComment": true requires an empty line before line comments
• "afterLineComment": true requires an empty line after line comments
• "allowBlockStart": true allows comments to appear at the start of block statements, function bodies, classes, switch statements, and class static blocks
• "allowBlockEnd": true allows comments to appear at the end of block statements, function bodies, classes, switch statements, and class static blocks
• "allowObjectStart": true allows comments to appear at the start of object literals
• "allowObjectEnd": true allows comments to appear at the end of object literals
• "allowArrayStart": true allows comments to appear at the start of array literals
• "allowArrayEnd": true allows comments to appear at the end of array literals
• "allowClassStart": true allows comments to appear at the start of classes
• "allowClassEnd": true allows comments to appear at the end of classes
• "applyDefaultIgnorePatterns" enables or disables the default comment patterns to be ignored by the rule
• "ignorePattern" custom patterns to be ignored by the rule
• "afterHashbangComment": true requires an empty line after hashbang comments

beforeBlockComment

Examples of incorrect code for this rule with the default { "beforeBlockComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true }]*/

var night = "long";
/* what a great and wonderful day */
var day = "great"

incorrect

Examples of correct code for this rule with the default { "beforeBlockComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true }]*/

var night = "long";

/* what a great and wonderful day */
var day = "great"

correct

afterBlockComment

Examples of incorrect code for this rule with the { "afterBlockComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true }]*/

var night = "long";

/* what a great and wonderful day */
var day = "great"

incorrect

Examples of correct code for this rule with the { "afterBlockComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true }]*/

var night = "long";

/* what a great and wonderful day */

var day = "great"

correct

beforeLineComment

Examples of incorrect code for this rule with the { "beforeLineComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true }]*/

var night = "long";
// what a great and wonderful day
var day = "great"

incorrect

Examples of correct code for this rule with the { "beforeLineComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true }]*/

var night = "long";

// what a great and wonderful day
var day = "great"

correct

afterLineComment

Examples of incorrect code for this rule with the { "afterLineComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true }]*/

var night = "long";
// what a great and wonderful day
var day = "great"

incorrect

Examples of correct code for this rule with the { "afterLineComment": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true }]*/

var night = "long";
// what a great and wonderful day

var day = "great"

correct

allowBlockStart

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

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowBlockStart": true }]*/

function foo(){
    // what a great and wonderful day
    var day = "great"
    return day;
}

if (bar) {
    // what a great and wonderful day
    foo();
}

class C {
    // what a great and wonderful day

    method() {
        // what a great and wonderful day
        foo();
    }

    static {
        // what a great and wonderful day
        foo();
    }
}

correct

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

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowBlockStart": true }]*/

function foo(){
    /* what a great and wonderful day */
    var day = "great"
    return day;
}

if (bar) {
    /* what a great and wonderful day */
    foo();
}

class C {
    /* what a great and wonderful day */

    method() {
        /* what a great and wonderful day */
        foo();
    }

    static {
        /* what a great and wonderful day */
        foo();
    }
}

switch (foo) {
  /* what a great and wonderful day */

  case 1:
    bar();
    break;
}

correct

allowBlockEnd

Examples of correct code for this rule with the { "afterLineComment": true, "allowBlockEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true, "allowBlockEnd": true }]*/

function foo(){
    var day = "great"
    return day;
    // what a great and wonderful day
}

if (bar) {
    foo();
    // what a great and wonderful day
}

class C {

    method() {
        foo();
        // what a great and wonderful day
    }

    static {
        foo();
        // what a great and wonderful day
    }

    // what a great and wonderful day
}

correct

Examples of correct code for this rule with the { "afterBlockComment": true, "allowBlockEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true, "allowBlockEnd": true }]*/

function foo(){
    var day = "great"
    return day;

    /* what a great and wonderful day */
}

if (bar) {
    foo();

    /* what a great and wonderful day */
}

class C {

    method() {
        foo();

        /* what a great and wonderful day */
    }

    static {
        foo();

        /* what a great and wonderful day */
    }

    /* what a great and wonderful day */
}

switch (foo) {
  case 1:
    bar();
    break;

  /* what a great and wonderful day */
}

correct

allowClassStart

Examples of incorrect code for this rule with the { "beforeLineComment": true, "allowClassStart": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": false }]*/

class foo {
        
// what a great and wonderful day
    day() {}
};

incorrect

Examples of correct code for this rule with the { "beforeLineComment": true, "allowClassStart": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": false }]*/

class foo {

    // what a great and wonderful day
    day() {}
};

correct

Examples of correct code for this rule with the { "beforeLineComment": true, "allowClassStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": true }]*/

class foo {
    // what a great and wonderful day
    day() {}
};

correct

Examples of incorrect code for this rule with the { "beforeBlockComment": true, "allowClassStart": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": false }]*/

class foo {
        
/* what a great and wonderful day */
    day() {}
};

incorrect

Examples of correct code for this rule with the { "beforeBlockComment": true, "allowClassStart": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": false }]*/

class foo {

    /* what a great and wonderful day */
    day() {}
};

correct

Examples of correct code for this rule with the { "beforeBlockComment": true, "allowClassStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": true }]*/

class foo {
    /* what a great and wonderful day */
    day() {}
};

correct

allowClassEnd

Examples of correct code for this rule with the { "afterLineComment": true, "allowClassEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true, "allowClassEnd": true }]*/

class foo {
    day() {}
    // what a great and wonderful day
};

correct

Examples of correct code for this rule with the { "afterBlockComment": true, "allowClassEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true, "allowClassEnd": true }]*/

class foo {
    day() {}

    /* what a great and wonderful day */
};

correct

allowObjectStart

Examples of correct code for this rule with the { "beforeLineComment": true, "allowObjectStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowObjectStart": true }]*/

var foo = {
    // what a great and wonderful day
    day: "great"
};

const {
    // what a great and wonderful day
    foo: someDay
} = {foo: "great"};

const {
    // what a great and wonderful day
    day
} = {day: "great"};

correct

Examples of correct code for this rule with the { "beforeBlockComment": true, "allowObjectStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowObjectStart": true }]*/

var foo = {
    /* what a great and wonderful day */
    day: "great"
};

const {
    /* what a great and wonderful day */
    foo: someDay
} = {foo: "great"};

const {
    /* what a great and wonderful day */
    day
} = {day: "great"};

correct

allowObjectEnd

Examples of correct code for this rule with the { "afterLineComment": true, "allowObjectEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true, "allowObjectEnd": true }]*/

var foo = {
    day: "great"
    // what a great and wonderful day
};

const {
    foo: someDay
    // what a great and wonderful day
} = {foo: "great"};

const {
    day
    // what a great and wonderful day
} = {day: "great"};

correct

Examples of correct code for this rule with the { "afterBlockComment": true, "allowObjectEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true, "allowObjectEnd": true }]*/

var foo = {
    day: "great"

    /* what a great and wonderful day */
};

const {
    foo: someDay

    /* what a great and wonderful day */
} = {foo: "great"};

const {
    day

    /* what a great and wonderful day */
} = {day: "great"};

correct

allowArrayStart

Examples of correct code for this rule with the { "beforeLineComment": true, "allowArrayStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeLineComment": true, "allowArrayStart": true }]*/

var day = [
    // what a great and wonderful day
    "great",
    "wonderful"
];

const [
    // what a great and wonderful day
    someDay
] = ["great", "not great"];

correct

Examples of correct code for this rule with the { "beforeBlockComment": true, "allowArrayStart": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "beforeBlockComment": true, "allowArrayStart": true }]*/

var day = [
    /* what a great and wonderful day */
    "great",
    "wonderful"
];

const [
    /* what a great and wonderful day */
    someDay
] = ["great", "not great"];

correct

allowArrayEnd

Examples of correct code for this rule with the { "afterLineComment": true, "allowArrayEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterLineComment": true, "allowArrayEnd": true }]*/

var day = [
    "great",
    "wonderful"
    // what a great and wonderful day
];

const [
    someDay
    // what a great and wonderful day
] = ["great", "not great"];

correct

Examples of correct code for this rule with the { "afterBlockComment": true, "allowArrayEnd": true } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterBlockComment": true, "allowArrayEnd": true }]*/

var day = [
    "great",
    "wonderful"

    /* what a great and wonderful day */
];

const [
    someDay

    /* what a great and wonderful day */
] = ["great", "not great"];

correct

ignorePattern

By default this rule ignores comments starting with the following words: eslint, jshint, jslint, istanbul, global, exported, jscs. To ignore more comments in addition to the defaults, set the ignorePattern option to a string pattern that will be passed to the RegExp constructor.

Examples of correct code for the ignorePattern option:

/*eslint @stylistic/js/lines-around-comment: ["error"]*/

foo();
/* eslint mentioned in this comment */
bar();

/*eslint @stylistic/js/lines-around-comment: ["error", { "ignorePattern": "pragma" }] */

foo();
/* a valid comment using pragma in it */

correct

Examples of incorrect code for the ignorePattern option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "ignorePattern": "pragma" }] */

1 + 1;
/* something else */

incorrect

applyDefaultIgnorePatterns

Default ignore patterns are applied even when ignorePattern is provided. If you want to omit default patterns, set this option to false.

Examples of correct code for the { "applyDefaultIgnorePatterns": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "ignorePattern": "pragma", applyDefaultIgnorePatterns: false }] */

foo();
/* a valid comment using pragma in it */

correct

Examples of incorrect code for the { "applyDefaultIgnorePatterns": false } option:

/*eslint @stylistic/js/lines-around-comment: ["error", { "applyDefaultIgnorePatterns": false }] */

foo();
/* eslint mentioned in comment */

incorrect

afterHashbangComment

Examples of incorrect code for this rule with the { "afterHashbangComment": true } option:

#!foo
var day = "great"

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterHashbangComment": true }] */

incorrect

Examples of correct code for this rule with the { "afterHashbangComment": true } option:

#!foo

var day = "great"

/*eslint @stylistic/js/lines-around-comment: ["error", { "afterHashbangComment": true }] */

correct

When Not To Use It

Many people enjoy a terser code style and don't mind comments bumping up against code. If you fall into that category this rule is not for you.