Enforce or disallow capitalization of the first letter of a comment
Some problems reported by this rule are automatically fixable by the --fix
command line option
Comments are useful for leaving information for future developers. In order for that information to be useful and not distracting, it is sometimes desirable for comments to follow a particular style. One element of comment formatting styles is whether the first word of a comment should be capitalized or lowercase.
In general, no comment style is any more or less valid than any others, but many developers would agree that a consistent style can improve a project’s maintainability.
This rule aims to enforce a consistent style of comments across your codebase, specifically by either requiring or disallowing a capitalized letter as the first word character in a comment. This rule will not issue warnings when non-cased letters are used.
By default, this rule will require a non-lowercase letter at the beginning of comments.
Examples of incorrect code for this rule:
Examples of correct code for this rule:
// Capitalized comment
// 1. Non-letter at beginning of comment
// 丈 Non-Latin character at beginning of comment
/* eslint semi:off */
/* eslint-env node */
/* eslint-disable */
/* eslint-enable */
/* istanbul ignore next */
/* jscs:enable */
/* jshint asi:true */
/* global foo */
/* globals foo */
/* exported myVar */
// eslint-disable-line
// eslint-disable-next-line
// https://github.com
This rule has two options: a string value "always"
or "never"
which determines whether capitalization of the first word of a comment should be required or forbidden, and optionally an object containing more configuration parameters for the rule.
Here are the supported object options:
ignorePattern
: A string representing a regular expression pattern of words that should be ignored by this rule. If the first word of a comment matches the pattern, this rule will not report that comment. ["jscs", "jshint", "eslint", "istanbul", "global", "globals", "exported"]
.ignoreInlineComments
: If this is true
, the rule will not report on comments in the middle of code. By default, this is false
.ignoreConsecutiveComments
: If this is true
, the rule will not report on a comment which violates the rule, as long as the comment immediately follows another comment. By default, this is false
.Here is an example configuration:
{
"capitalized-comments": [
"error",
"always",
{
"ignorePattern": "pragma|ignored",
"ignoreInlineComments": true
}
]
}
"always"
Using the "always"
option means that this rule will report any comments which start with a lowercase letter. This is the default configuration for this rule.
Note that configuration comments and comments which start with URLs are never reported.
Examples of incorrect code for this rule:
Examples of correct code for this rule:
/* eslint capitalized-comments: ["error", "always"] */
// Capitalized comment
// 1. Non-letter at beginning of comment
// 丈 Non-Latin character at beginning of comment
/* eslint semi:off */
/* eslint-env node */
/* eslint-disable */
/* eslint-enable */
/* istanbul ignore next */
/* jscs:enable */
/* jshint asi:true */
/* global foo */
/* globals foo */
/* exported myVar */
// eslint-disable-line
// eslint-disable-next-line
// https://github.com
"never"
Using the "never"
option means that this rule will report any comments which start with an uppercase letter.
Examples of incorrect code with the "never"
option:
Examples of correct code with the "never"
option:
ignorePattern
The ignorePattern
object takes a string value, which is used as a regular expression applied to the first word of a comment.
Examples of correct code with the "ignorePattern"
option set to "pragma"
:
ignoreInlineComments
Setting the ignoreInlineComments
option to true
means that comments in the middle of code (with a token on the same line as the beginning of the comment, and another token on the same line as the end of the comment) will not be reported by this rule.
Examples of correct code with the "ignoreInlineComments"
option set to true
:
ignoreConsecutiveComments
If the ignoreConsecutiveComments
option is set to true
, then comments which otherwise violate the rule will not be reported as long as they immediately follow another comment. This can be applied more than once.
Examples of correct code with ignoreConsecutiveComments
set to true
:
/* eslint capitalized-comments: ["error", "always", { "ignoreConsecutiveComments": true }] */
// This comment is valid since it has the correct capitalization.
// this comment is ignored since it follows another comment,
// and this one as well because it follows yet another comment.
/* Here is a block comment which has the correct capitalization, */
/* but this one is ignored due to being consecutive; */
/*
* in fact, even if any of these are multi-line, that is fine too.
*/
Examples of incorrect code with ignoreConsecutiveComments
set to true
:
If you wish to have a different configuration for line comments and block comments, you can do so by using two different object configurations (note that the capitalization option will be enforced consistently for line and block comments):
{
"capitalized-comments": [
"error",
"always",
{
"line": {
"ignorePattern": "pragma|ignored",
},
"block": {
"ignoreInlineComments": true,
"ignorePattern": "ignored"
}
}
]
}
Examples of incorrect code with different line and block comment configuration:
Examples of correct code with different line and block comment configuration:
This rule can be disabled if you do not care about the grammatical style of comments in your codebase.
This rule was introduced in ESLint v3.11.0.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/capitalized-comments