eslint/docs/rules/no-setter-return.md

   1 # Disallow returning values from setters (no-setter-return)
   2
   3 Setters cannot return values.
   4
   5 While returning a value from a setter does not produce an error, the returned value is being ignored. Therefore, returning a value from a setter is either unnecessary or a possible error, since the returned value cannot be used.
   6
   7 ## Rule Details
   8
   9 This rule disallows returning values from setters and reports `return` statements in setter functions.
  10
  11 Only `return` without a value is allowed, as it's a control flow statement.
  12
  13 This rule checks setters in:
  14
  15 * Object literals.
  16 * Class declarations and class expressions.
  17 * Property descriptors in `Object.create`, `Object.defineProperty`, `Object.defineProperties`, and `Reflect.defineProperty` methods of the global objects.
  18
  19 Examples of **incorrect** code for this rule:
  20
  21 ```js
  22 /*eslint no-setter-return: "error"*/
  23
  24 var foo = {
  25     set a(value) {
  26         this.val = value;
  27         return value;
  28     }
  29 };
  30
  31 class Foo {
  32     set a(value) {
  33         this.val = value * 2;
  34         return this.val;
  35     }
  36 }
  37
  38 const Bar = class {
  39     static set a(value) {
  40         if (value < 0) {
  41             this.val = 0;
  42             return 0;
  43         }
  44         this.val = value;
  45     }
  46 };
  47
  48 Object.defineProperty(foo, "bar", {
  49     set(value) {
  50         if (value < 0) {
  51             return false;
  52         }
  53         this.val = value;
  54     }
  55 });
  56 ```
  57
  58 Examples of **correct** code for this rule:
  59
  60 ```js
  61 /*eslint no-setter-return: "error"*/
  62
  63 var foo = {
  64     set a(value) {
  65         this.val = value;
  66     }
  67 };
  68
  69 class Foo {
  70     set a(value) {
  71         this.val = value * 2;
  72     }
  73 }
  74
  75 const Bar = class {
  76     static set a(value) {
  77         if (value < 0) {
  78             this.val = 0;
  79             return;
  80         }
  81         this.val = value;
  82     }
  83 };
  84
  85 Object.defineProperty(foo, "bar", {
  86     set(value) {
  87         if (value < 0) {
  88             throw new Error("Negative value.");
  89         }
  90         this.val = value;
  91     }
  92 });
  93 ```
  94
  95 ## Further Reading
  96
  97 * [MDN setter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set)
  98
  99 ## Related Rules
 100
 101 * [getter-return](getter-return.md)