Require empty lines around comments
Some problems reported by this rule are automatically fixable by the --fix command line option
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.
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.
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 ruleExamples of incorrect code for this rule with the default { "beforeBlockComment": true } option:
/*eslint lines-around-comment: ["error", { "beforeBlockComment": true }]*/
var night = "long";
/* what a great and wonderful day */
var day = "great"
Examples of correct code for this rule with the default { "beforeBlockComment": true } option:
/*eslint lines-around-comment: ["error", { "beforeBlockComment": true }]*/
var night = "long";
/* what a great and wonderful day */
var day = "great"
Examples of incorrect code for this rule with the { "afterBlockComment": true } option:
/*eslint lines-around-comment: ["error", { "afterBlockComment": true }]*/
var night = "long";
/* what a great and wonderful day */
var day = "great"
Examples of correct code for this rule with the { "afterBlockComment": true } option:
/*eslint lines-around-comment: ["error", { "afterBlockComment": true }]*/
var night = "long";
/* what a great and wonderful day */
var day = "great"
Examples of incorrect code for this rule with the { "beforeLineComment": true } option:
/*eslint lines-around-comment: ["error", { "beforeLineComment": true }]*/
var night = "long";
// what a great and wonderful day
var day = "great"
Examples of correct code for this rule with the { "beforeLineComment": true } option:
/*eslint lines-around-comment: ["error", { "beforeLineComment": true }]*/
var night = "long";
// what a great and wonderful day
var day = "great"
Examples of incorrect code for this rule with the { "afterLineComment": true } option:
/*eslint lines-around-comment: ["error", { "afterLineComment": true }]*/
var night = "long";
// what a great and wonderful day
var day = "great"
Examples of correct code for this rule with the { "afterLineComment": true } option:
/*eslint lines-around-comment: ["error", { "afterLineComment": true }]*/
var night = "long";
// what a great and wonderful day
var day = "great"
Examples of correct code for this rule with the { "beforeLineComment": true, "allowBlockStart": true } options:
/*eslint 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();
}
}
Examples of correct code for this rule with the { "beforeBlockComment": true, "allowBlockStart": true } options:
/*eslint 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;
}
Examples of correct code for this rule with the { "afterLineComment": true, "allowBlockEnd": true } option:
/*eslint 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
}
Examples of correct code for this rule with the { "afterBlockComment": true, "allowBlockEnd": true } option:
/*eslint 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 */
}
Examples of incorrect code for this rule with the { "beforeLineComment": true, "allowClassStart": false } option:
/*eslint lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": false }]*/
class foo {
// what a great and wonderful day
day() {}
};
Examples of correct code for this rule with the { "beforeLineComment": true, "allowClassStart": false } option:
/*eslint lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": false }]*/
class foo {
// what a great and wonderful day
day() {}
};
Examples of correct code for this rule with the { "beforeLineComment": true, "allowClassStart": true } option:
/*eslint lines-around-comment: ["error", { "beforeLineComment": true, "allowClassStart": true }]*/
class foo {
// what a great and wonderful day
day() {}
};
Examples of incorrect code for this rule with the { "beforeBlockComment": true, "allowClassStart": false } option:
/*eslint lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": false }]*/
class foo {
/* what a great and wonderful day */
day() {}
};
Examples of correct code for this rule with the { "beforeBlockComment": true, "allowClassStart": false } option:
/*eslint lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": false }]*/
class foo {
/* what a great and wonderful day */
day() {}
};
Examples of correct code for this rule with the { "beforeBlockComment": true, "allowClassStart": true } option:
/*eslint lines-around-comment: ["error", { "beforeBlockComment": true, "allowClassStart": true }]*/
class foo {
/* what a great and wonderful day */
day() {}
};
Examples of correct code for this rule with the { "afterLineComment": true, "allowClassEnd": true } option:
/*eslint lines-around-comment: ["error", { "afterLineComment": true, "allowClassEnd": true }]*/
class foo {
day() {}
// what a great and wonderful day
};
Examples of correct code for this rule with the { "afterBlockComment": true, "allowClassEnd": true } option:
/*eslint lines-around-comment: ["error", { "afterBlockComment": true, "allowClassEnd": true }]*/
class foo {
day() {}
/* what a great and wonderful day */
};
Examples of correct code for this rule with the { "beforeLineComment": true, "allowObjectStart": true } option:
/*eslint 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"};
Examples of correct code for this rule with the { "beforeBlockComment": true, "allowObjectStart": true } option:
/*eslint 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"};
Examples of correct code for this rule with the { "afterLineComment": true, "allowObjectEnd": true } option:
/*eslint 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"};
Examples of correct code for this rule with the { "afterBlockComment": true, "allowObjectEnd": true } option:
/*eslint 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"};
Examples of correct code for this rule with the { "beforeLineComment": true, "allowArrayStart": true } option:
/*eslint 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"];
Examples of correct code for this rule with the { "beforeBlockComment": true, "allowArrayStart": true } option:
/*eslint 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"];
Examples of correct code for this rule with the { "afterLineComment": true, "allowArrayEnd": true } option:
/*eslint 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"];
Examples of correct code for this rule with the { "afterBlockComment": true, "allowArrayEnd": true } option:
/*eslint 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"];
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 lines-around-comment: ["error"]*/
foo();
/* eslint mentioned in this comment */,
bar();
/*eslint lines-around-comment: ["error", { "ignorePattern": "pragma" }] */
foo();
/* a valid comment using pragma in it */
Examples of incorrect code for the ignorePattern option:
/*eslint lines-around-comment: ["error", { "ignorePattern": "pragma" }] */
1 + 1;
/* something else */
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 lines-around-comment: ["error", { "ignorePattern": "pragma", applyDefaultIgnorePatterns: false }] */
foo();
/* a valid comment using pragma in it */
Examples of incorrect code for the { "applyDefaultIgnorePatterns": false } option:
/*eslint lines-around-comment: ["error", { "applyDefaultIgnorePatterns": false }] */
foo();
/* eslint mentioned in comment */
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.
This rule was introduced in ESLint v0.22.0.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/lines-around-comment