|
| 1 | +# Require grouped accessor pairs in object literals and classes (grouped-accessor-pairs) |
| 2 | + |
| 3 | +A getter and setter for the same property don't necessarily have to be defined adjacent to each other. |
| 4 | + |
| 5 | +For example, the following statements would create the same object: |
| 6 | + |
| 7 | +```js |
| 8 | +var o = { |
| 9 | + get a() { |
| 10 | + return this.val; |
| 11 | + }, |
| 12 | + set a(value) { |
| 13 | + this.val = value; |
| 14 | + }, |
| 15 | + b: 1 |
| 16 | +}; |
| 17 | + |
| 18 | +var o = { |
| 19 | + get a() { |
| 20 | + return this.val; |
| 21 | + }, |
| 22 | + b: 1, |
| 23 | + set a(value) { |
| 24 | + this.val = value; |
| 25 | + } |
| 26 | +}; |
| 27 | +``` |
| 28 | + |
| 29 | +While it is allowed to define the pair for a getter or a setter anywhere in an object or class definition, it's considered a best practice to group accessor functions for the same property. |
| 30 | + |
| 31 | +In other words, if a property has a getter and a setter, the setter should be defined right after the getter, or vice versa. |
| 32 | + |
| 33 | +## Rule Details |
| 34 | + |
| 35 | +This rule requires grouped definitions of accessor functions for the same property in object literals, class declarations and class expressions. |
| 36 | + |
| 37 | +Optionally, this rule can also enforce consistent order (`getBeforeSet` or `setBeforeGet`). |
| 38 | + |
| 39 | +This rule does not enforce the existence of the pair for a getter or a setter. See [accessor-pairs](accessor-pairs.md) if you also want to enforce getter/setter pairs. |
| 40 | + |
| 41 | +Examples of **incorrect** code for this rule: |
| 42 | + |
| 43 | +```js |
| 44 | +/*eslint grouped-accessor-pairs: "error"*/ |
| 45 | + |
| 46 | +var foo = { |
| 47 | + get a() { |
| 48 | + return this.val; |
| 49 | + }, |
| 50 | + b: 1, |
| 51 | + set a(value) { |
| 52 | + this.val = value; |
| 53 | + } |
| 54 | +}; |
| 55 | + |
| 56 | +var bar = { |
| 57 | + set b(value) { |
| 58 | + this.val = value; |
| 59 | + }, |
| 60 | + a: 1, |
| 61 | + get b() { |
| 62 | + return this.val; |
| 63 | + } |
| 64 | +} |
| 65 | + |
| 66 | +class Foo { |
| 67 | + set a(value) { |
| 68 | + this.val = value; |
| 69 | + } |
| 70 | + b(){} |
| 71 | + get a() { |
| 72 | + return this.val; |
| 73 | + } |
| 74 | +} |
| 75 | + |
| 76 | +const Bar = class { |
| 77 | + static get a() { |
| 78 | + return this.val; |
| 79 | + } |
| 80 | + b(){} |
| 81 | + static set a(value) { |
| 82 | + this.val = value; |
| 83 | + } |
| 84 | +} |
| 85 | +``` |
| 86 | + |
| 87 | +Examples of **correct** code for this rule: |
| 88 | + |
| 89 | +```js |
| 90 | +/*eslint grouped-accessor-pairs: "error"*/ |
| 91 | + |
| 92 | +var foo = { |
| 93 | + get a() { |
| 94 | + return this.val; |
| 95 | + }, |
| 96 | + set a(value) { |
| 97 | + this.val = value; |
| 98 | + }, |
| 99 | + b: 1 |
| 100 | +}; |
| 101 | + |
| 102 | +var bar = { |
| 103 | + set b(value) { |
| 104 | + this.val = value; |
| 105 | + }, |
| 106 | + get b() { |
| 107 | + return this.val; |
| 108 | + }, |
| 109 | + a: 1 |
| 110 | +} |
| 111 | + |
| 112 | +class Foo { |
| 113 | + set a(value) { |
| 114 | + this.val = value; |
| 115 | + } |
| 116 | + get a() { |
| 117 | + return this.val; |
| 118 | + } |
| 119 | + b(){} |
| 120 | +} |
| 121 | + |
| 122 | +const Bar = class { |
| 123 | + static get a() { |
| 124 | + return this.val; |
| 125 | + } |
| 126 | + static set a(value) { |
| 127 | + this.val = value; |
| 128 | + } |
| 129 | + b(){} |
| 130 | +} |
| 131 | +``` |
| 132 | + |
| 133 | +## Options |
| 134 | + |
| 135 | +This rule has a string option: |
| 136 | + |
| 137 | +* `"anyOrder"` (default) does not enforce order. |
| 138 | +* `"getBeforeSet"` if a property has both getter and setter, requires the getter to be defined before the setter. |
| 139 | +* `"setBeforeGet"` if a property has both getter and setter, requires the setter to be defined before the getter. |
| 140 | + |
| 141 | +### getBeforeSet |
| 142 | + |
| 143 | +Examples of **incorrect** code for this rule with the `"getBeforeSet"` option: |
| 144 | + |
| 145 | +```js |
| 146 | +/*eslint grouped-accessor-pairs: ["error", "getBeforeSet"]*/ |
| 147 | + |
| 148 | +var foo = { |
| 149 | + set a(value) { |
| 150 | + this.val = value; |
| 151 | + }, |
| 152 | + get a() { |
| 153 | + return this.val; |
| 154 | + } |
| 155 | +}; |
| 156 | + |
| 157 | +class Foo { |
| 158 | + set a(value) { |
| 159 | + this.val = value; |
| 160 | + } |
| 161 | + get a() { |
| 162 | + return this.val; |
| 163 | + } |
| 164 | +} |
| 165 | + |
| 166 | +const Bar = class { |
| 167 | + static set a(value) { |
| 168 | + this.val = value; |
| 169 | + } |
| 170 | + static get a() { |
| 171 | + return this.val; |
| 172 | + } |
| 173 | +} |
| 174 | +``` |
| 175 | + |
| 176 | +Examples of **correct** code for this rule with the `"getBeforeSet"` option: |
| 177 | + |
| 178 | +```js |
| 179 | +/*eslint grouped-accessor-pairs: ["error", "getBeforeSet"]*/ |
| 180 | + |
| 181 | +var foo = { |
| 182 | + get a() { |
| 183 | + return this.val; |
| 184 | + }, |
| 185 | + set a(value) { |
| 186 | + this.val = value; |
| 187 | + } |
| 188 | +}; |
| 189 | + |
| 190 | +class Foo { |
| 191 | + get a() { |
| 192 | + return this.val; |
| 193 | + } |
| 194 | + set a(value) { |
| 195 | + this.val = value; |
| 196 | + } |
| 197 | +} |
| 198 | + |
| 199 | +const Bar = class { |
| 200 | + static get a() { |
| 201 | + return this.val; |
| 202 | + } |
| 203 | + static set a(value) { |
| 204 | + this.val = value; |
| 205 | + } |
| 206 | +} |
| 207 | +``` |
| 208 | + |
| 209 | +### setBeforeGet |
| 210 | + |
| 211 | +Examples of **incorrect** code for this rule with the `"setBeforeGet"` option: |
| 212 | + |
| 213 | +```js |
| 214 | +/*eslint grouped-accessor-pairs: ["error", "setBeforeGet"]*/ |
| 215 | + |
| 216 | +var foo = { |
| 217 | + get a() { |
| 218 | + return this.val; |
| 219 | + }, |
| 220 | + set a(value) { |
| 221 | + this.val = value; |
| 222 | + } |
| 223 | +}; |
| 224 | + |
| 225 | +class Foo { |
| 226 | + get a() { |
| 227 | + return this.val; |
| 228 | + } |
| 229 | + set a(value) { |
| 230 | + this.val = value; |
| 231 | + } |
| 232 | +} |
| 233 | + |
| 234 | +const Bar = class { |
| 235 | + static get a() { |
| 236 | + return this.val; |
| 237 | + } |
| 238 | + static set a(value) { |
| 239 | + this.val = value; |
| 240 | + } |
| 241 | +} |
| 242 | +``` |
| 243 | + |
| 244 | +Examples of **correct** code for this rule with the `"setBeforeGet"` option: |
| 245 | + |
| 246 | +```js |
| 247 | +/*eslint grouped-accessor-pairs: ["error", "setBeforeGet"]*/ |
| 248 | + |
| 249 | +var foo = { |
| 250 | + set a(value) { |
| 251 | + this.val = value; |
| 252 | + }, |
| 253 | + get a() { |
| 254 | + return this.val; |
| 255 | + } |
| 256 | +}; |
| 257 | + |
| 258 | +class Foo { |
| 259 | + set a(value) { |
| 260 | + this.val = value; |
| 261 | + } |
| 262 | + get a() { |
| 263 | + return this.val; |
| 264 | + } |
| 265 | +} |
| 266 | + |
| 267 | +const Bar = class { |
| 268 | + static set a(value) { |
| 269 | + this.val = value; |
| 270 | + } |
| 271 | + static get a() { |
| 272 | + return this.val; |
| 273 | + } |
| 274 | +} |
| 275 | +``` |
| 276 | + |
| 277 | +## Known Limitations |
| 278 | + |
| 279 | +Due to the limits of static analysis, this rule does not account for possible side effects and in certain cases |
| 280 | +might require or miss to require grouping or order for getters/setters that have a computed key, like in the following example: |
| 281 | + |
| 282 | +```js |
| 283 | +/*eslint grouped-accessor-pairs: "error"*/ |
| 284 | + |
| 285 | +var a = 1; |
| 286 | + |
| 287 | +// false warning (false positive) |
| 288 | +var foo = { |
| 289 | + get [a++]() { |
| 290 | + return this.val; |
| 291 | + }, |
| 292 | + b: 1, |
| 293 | + set [a++](value) { |
| 294 | + this.val = value; |
| 295 | + } |
| 296 | +}; |
| 297 | + |
| 298 | +// missed warning (false negative) |
| 299 | +var bar = { |
| 300 | + get [++a]() { |
| 301 | + return this.val; |
| 302 | + }, |
| 303 | + b: 1, |
| 304 | + set [a](value) { |
| 305 | + this.val = value; |
| 306 | + } |
| 307 | +}; |
| 308 | +``` |
| 309 | + |
| 310 | +Also, this rule does not report any warnings for properties that have duplicate getters or setters. |
| 311 | + |
| 312 | +See [no-dupe-keys](no-dupe-keys.md) if you also want to disallow duplicate keys in object literals. |
| 313 | + |
| 314 | +See [no-dupe-class-members](no-dupe-class-members.md) if you also want to disallow duplicate names in class definitions. |
| 315 | + |
| 316 | +## Further Reading |
| 317 | + |
| 318 | +* [Object Setters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set) |
| 319 | +* [Object Getters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get) |
| 320 | +* [Classes](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) |
| 321 | + |
| 322 | +## Related Rules |
| 323 | + |
| 324 | +* [accessor-pairs](accessor-pairs.md) |
| 325 | +* [no-dupe-keys](no-dupe-keys.md) |
| 326 | +* [no-dupe-class-members](no-dupe-class-members.md) |
0 commit comments