Requires or disallows a whitespace (space or tab) beginning a comment (spaced-comment)

Some style guides require or disallow a whitespace immediately after the initial // or /* of a comment. Whitespace after the // or /* makes it easier to read text in comments. On the other hand, commenting out code is easier without having to put a whitespace right after the // or /*.

Fixable: This rule is automatically fixable using the --fix flag on the command line.

Rule Details

This rule will enforce consistency of spacing after the start of a comment // or /*. It also provides several exceptions for various documentation styles.

Options

The rule takes two options. The first is a string which be either "always" or "never". If you pass "always" then the // or /* must be followed by at least once whitespace. If "never" then there should be no whitespace following. The default is "always".

Here is an example of how to configure the rule with this option:

"spaced-comment": [2, "always"]

Exceptions

This rule can also take a 2nd option, an object with either of the following keys: "exceptions" and "markers".

The "exceptions" value is an array of string patterns which are considered exceptions to the rule. Please note that exceptions are ignored if the first argument is "never".

"spaced-comment": [2, "always", { "exceptions": ["-", "+"] }]

The "markers" value is an array of string patterns which are considered markers for docblock-style comments, such as an additional /, used to denote documentation read by doxygen, vsdoc, etc. which must have additional characters. The "markers" array will apply regardless of the value of the first argument, e.g. "always" or "never".

"spaced-comment": [2, "always", { "markers": ["/"] }]

The difference between a marker and an exception is that a marker only appears at the beginning of the comment whereas exceptions can occur anywhere in the comment string.

You can also define separate exceptions and markers for block and line comments:

"spaced-comment": [2, "always", {
    "line": {
        "markers": ["/"],
        "exceptions": ["-", "+"]
    },
    "block": {
        "markers": ["!"],
        "exceptions": ["*"]
    }
}]

Examples

The following patterns are considered problems:

/*eslint spaced-comment: [2, "never"]*/

// This is a comment with a whitespace at the beginning      /*error Unexpected space or tab after '//' in comment.*/

/* This is a comment with a whitespace at the beginning */   /*error Unexpected space or tab after '/*' in comment.*/

/* \nThis is a comment with a whitespace at the beginning */ /*error Unexpected space or tab after '/*' in comment.*/

/*eslint spaced-comment: [2, "always"]*/                     /*error Expected space or tab after '/*' in comment.*/

//This is a comment with no whitespace at the beginning      /*error Expected space or tab after '//' in comment.*/

/*This is a comment with no whitespace at the beginning */   /*error Expected space or tab after '/*' in comment.*/

/* eslint spaced-comment: [2, "always", { "block": { "exceptions": ["-"] } }] */

//--------------    /*error Expected space or tab after '//' in comment.*/
// Comment block
//--------------    /*error Expected space or tab after '//' in comment.*/

/* eslint spaced-comment: [2, "always", { "exceptions": ["-", "+"] }] */

//------++++++++    /*error Expected exception block, space or tab after '//' in comment.*/
// Comment block
//------++++++++    /*error Expected exception block, space or tab after '//' in comment.*/

/* eslint spaced-comment: [2, "always", { "markers": ["/"] }] */

///This is a comment with a marker but without whitespace  /*error Expected space or tab after '///' in comment.*/

/* eslint spaced-comment: [2, "always", { "exceptions": ["-", "+"] }] */

/*------++++++++*/     /*error Expected exception block, space or tab after '/*' in comment.*/
/* Comment block */
/*------++++++++*/     /*error Expected exception block, space or tab after '/*' in comment.*/

/* eslint spaced-comment: [2, "always", { "line": { "exceptions": ["-+"] } }] */

/*-+-+-+-+-+-+-+*/     /*error Expected space or tab after '/*' in comment.*/
// Comment block
/*-+-+-+-+-+-+-+*/     /*error Expected space or tab after '/*' in comment.*/

The following patterns are not considered problems:

/* eslint spaced-comment: [2, "always"] */

// This is a comment with a whitespace at the beginning

/* This is a comment with a whitespace at the beginning */

/*
 * This is a comment with a whitespace at the beginning
 */

/*
This comment has a newline
*/

/*eslint spaced-comment: [2, "never"]*/

/*This is a comment with no whitespace at the beginning */

/* eslint spaced-comment: [2, "always", { "exceptions": ["-"] }] */

//--------------
// Comment block
//--------------

/* eslint spaced-comment: [2, "always", { "line": { "exceptions": ["-"] } }] */

//--------------
// Comment block
//--------------

/* eslint spaced-comment: [2, "always", { "exceptions": ["-+"] }] */

//-+-+-+-+-+-+-+
// Comment block
//-+-+-+-+-+-+-+

/*-+-+-+-+-+-+-+*/
// Comment block
/*-+-+-+-+-+-+-+*/

/* eslint spaced-comment: [2, "always", { "block": { "exceptions": ["-+"] } }] */

/*-+-+-+-+-+-+-+*/
// Comment block
/*-+-+-+-+-+-+-+*/

/* eslint spaced-comment: [2, "always", { "exceptions": ["*"] }] */

/****************
 * Comment block
 ****************/

/* eslint spaced-comment: [2, "always", { "markers": ["/"] }] */

/// This is a comment with a marker

/*eslint spaced-comment: [2, "never", { "markers": ["!<"] }]*/

//!<This is a comment with a marker
/*!<this is a block comment with a marker
subsequent lines are ignored
*/

/* eslint spaced-comment: [2, "always", { "markers": ["global"] }] */

/*global ABC*/

/* eslint spaced-comment: [2, "always"] */

/**
* I am jsdoc
*/

/*eslint spaced-comment: [2, "never"]*/

/**
* I am jsdoc
*/

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