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

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