eslint/docs/rules/new-parens.md

   1 # require parentheses when invoking a constructor with no arguments (new-parens)
   2
   3 JavaScript allows the omission of parentheses when invoking a function via the `new` keyword and the constructor has no arguments. However, some coders believe that omitting the parentheses is inconsistent with the rest of the language and thus makes code less clear.
   4
   5 ```js
   6 var person = new Person;
   7 ```
   8
   9 ## Rule Details
  10
  11 This rule can enforce or disallow parentheses when invoking a constructor with no arguments using the `new` keyword.
  12
  13 ## Options
  14
  15 This rule takes one option.
  16
  17 - `"always"` enforces parenthesis after a new constructor with no arguments (default)
  18 - `"never"` enforces no parenthesis after a new constructor with no arguments
  19
  20 ### always
  21
  22 Examples of **incorrect** code for this rule with the `"always"` option:
  23
  24 ```js
  25 /*eslint new-parens: "error"*/
  26
  27 var person = new Person;
  28 var person = new (Person);
  29 ```
  30
  31 Examples of **correct** code for this rule with the `"always"` option:
  32
  33 ```js
  34 /*eslint new-parens: "error"*/
  35
  36 var person = new Person();
  37 var person = new (Person)();
  38 ```
  39
  40 ### never
  41
  42 Examples of **incorrect** code for this rule with the `"never"` option:
  43
  44 ```js
  45 /*eslint new-parens: ["error", "never"]*/
  46
  47 var person = new Person();
  48 var person = new (Person)();
  49 ```
  50
  51 Examples of **correct** code for this rule with the `"never"` option:
  52
  53 ```js
  54 /*eslint new-parens: ["error", "never"]*/
  55
  56 var person = new Person;
  57 var person = (new Person);
  58 var person = new Person("Name");
  59 ```