eslint/docs/rules/max-lines.md

   1 # enforce a maximum file length (max-lines)
   2
   3 Some people consider large files a code smell. Large files tend to do a lot of things and can make it hard following what's going. While there is not an objective maximum number of lines considered acceptable in a file, most people would agree it should not be in the thousands. Recommendations usually range from 100 to 500 lines.
   4
   5 ## Rule Details
   6
   7 This rule enforces a maximum number of lines per file, in order to aid in maintainability and reduce complexity.
   8
   9 Please note that most editors show an additional empty line at the end if the file ends with a line break. This rule does not count that extra line.
  10
  11 ## Options
  12
  13 This rule has a number or object option:
  14
  15 * `"max"` (default `300`) enforces a maximum number of lines in a file
  16
  17 * `"skipBlankLines": true` ignore lines made up purely of whitespace.
  18
  19 * `"skipComments": true` ignore lines containing just comments
  20
  21 ### code
  22
  23 Examples of **incorrect** code for this rule with a max value of `2`:
  24
  25 ```js
  26 /*eslint max-lines: ["error", 2]*/
  27 var a,
  28     b,
  29     c;
  30 ```
  31
  32 ```js
  33 /*eslint max-lines: ["error", 2]*/
  34
  35 var a,
  36     b,c;
  37 ```
  38
  39 ```js
  40 /*eslint max-lines: ["error", 2]*/
  41 // a comment
  42 var a,
  43     b,c;
  44 ```
  45
  46 Examples of **correct** code for this rule with a max value of `2`:
  47
  48 ```js
  49 /*eslint max-lines: ["error", 2]*/
  50 var a,
  51     b, c;
  52 ```
  53
  54 ```js
  55 /*eslint max-lines: ["error", 2]*/
  56
  57 var a, b, c;
  58 ```
  59
  60 ```js
  61 /*eslint max-lines: ["error", 2]*/
  62 // a comment
  63 var a, b, c;
  64 ```
  65
  66 ### skipBlankLines
  67
  68 Examples of **incorrect** code for this rule with the `{ "skipBlankLines": true }` option:
  69
  70 ```js
  71 /*eslint max-lines: ["error", {"max": 2, "skipBlankLines": true}]*/
  72
  73 var a,
  74     b,
  75     c;
  76 ```
  77
  78 Examples of **correct** code for this rule with the `{ "skipBlankLines": true }` option:
  79
  80 ```js
  81 /*eslint max-lines: ["error", {"max": 2, "skipBlankLines": true}]*/
  82
  83 var a,
  84     b, c;
  85 ```
  86
  87 ### skipComments
  88
  89 Examples of **incorrect** code for this rule with the `{ "skipComments": true }` option:
  90
  91 ```js
  92 /*eslint max-lines: ["error", {"max": 2, "skipComments": true}]*/
  93 // a comment
  94 var a,
  95     b,
  96     c;
  97 ```
  98
  99 Examples of **correct** code for this rule with the `{ "skipComments": true }` option:
 100
 101 ```js
 102 /*eslint max-lines: ["error", {"max": 2, "skipComments": true}]*/
 103 // a comment
 104 var a,
 105     b, c;
 106 ```
 107
 108 ## When Not To Use It
 109
 110 You can turn this rule off if you are not concerned with the number of lines in your files.
 111
 112 ## Further reading
 113
 114 * [Software Module size and file size](https://web.archive.org/web/20160725154648/http://www.mind2b.com/component/content/article/24-software-module-size-and-file-size)
 115
 116 ## Related Rules
 117
 118 * [complexity](complexity.md)
 119 * [max-depth](max-depth.md)
 120 * [max-lines-per-function](max-lines-per-function.md)
 121 * [max-nested-callbacks](max-nested-callbacks.md)
 122 * [max-params](max-params.md)
 123 * [max-statements](max-statements.md)
 124
 125 ## Compatibility
 126
 127 * **JSCS**: [maximumNumberOfLines](https://jscs-dev.github.io/rule/maximumNumberOfLines)