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

   1 ---
   2 title: no-setter-return
   3 layout: doc
   4 rule_type: problem
   5 related_rules:
   6 - getter-return
   7 further_reading:
   8 - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set
   9 ---
  10
  11
  12
  13 Setters cannot return values.
  14
  15 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.
  16
  17 ## Rule Details
  18
  19 This rule disallows returning values from setters and reports `return` statements in setter functions.
  20
  21 Only `return` without a value is allowed, as it's a control flow statement.
  22
  23 This rule checks setters in:
  24
  25 * Object literals.
  26 * Class declarations and class expressions.
  27 * Property descriptors in `Object.create`, `Object.defineProperty`, `Object.defineProperties`, and `Reflect.defineProperty` methods of the global objects.
  28
  29 Examples of **incorrect** code for this rule:
  30
  31 ::: incorrect
  32
  33 ```js
  34 /*eslint no-setter-return: "error"*/
  35
  36 var foo = {
  37     set a(value) {
  38         this.val = value;
  39         return value;
  40     }
  41 };
  42
  43 class Foo {
  44     set a(value) {
  45         this.val = value * 2;
  46         return this.val;
  47     }
  48 }
  49
  50 const Bar = class {
  51     static set a(value) {
  52         if (value < 0) {
  53             this.val = 0;
  54             return 0;
  55         }
  56         this.val = value;
  57     }
  58 };
  59
  60 Object.defineProperty(foo, "bar", {
  61     set(value) {
  62         if (value < 0) {
  63             return false;
  64         }
  65         this.val = value;
  66     }
  67 });
  68 ```
  69
  70 :::
  71
  72 Examples of **correct** code for this rule:
  73
  74 ::: correct
  75
  76 ```js
  77 /*eslint no-setter-return: "error"*/
  78
  79 var foo = {
  80     set a(value) {
  81         this.val = value;
  82     }
  83 };
  84
  85 class Foo {
  86     set a(value) {
  87         this.val = value * 2;
  88     }
  89 }
  90
  91 const Bar = class {
  92     static set a(value) {
  93         if (value < 0) {
  94             this.val = 0;
  95             return;
  96         }
  97         this.val = value;
  98     }
  99 };
 100
 101 Object.defineProperty(foo, "bar", {
 102     set(value) {
 103         if (value < 0) {
 104             throw new Error("Negative value.");
 105         }
 106         this.val = value;
 107     }
 108 });
 109 ```
 110
 111 :::