accessor-pairs
Enforce getter and setter pairs in objects and classes
It’s a common mistake in JavaScript to create an object with just a setter for a property but never have a corresponding getter defined for it. Without a getter, you cannot read the property, so it ends up not being used.
Here are some examples:
// Bad
var o = {
set a(value) {
this.val = value;
}
};
// Good
var o = {
set a(value) {
this.val = value;
},
get a() {
return this.val;
}
};
This rule warns if setters are defined without getters. Using an option getWithoutSet, it will warn if you have a getter without a setter also.
Rule Details
This rule enforces a style where it requires to have a getter for every property which has a setter defined.
By activating the option getWithoutSet it enforces the presence of a setter for every property which has a getter defined.
This rule always checks object literals and property descriptors. By default, it also checks class declarations and class expressions.
Options
setWithoutGetset totruewill warn for setters without getters (Defaulttrue).getWithoutSetset totruewill warn for getters without setters (Defaultfalse).enforceForClassMembersset totrueadditionally applies this rule to class getters/setters (Defaulttrue). SetenforceForClassMemberstofalseif you want this rule to ignore class declarations and class expressions.
setWithoutGet
Examples of incorrect code for the default { "setWithoutGet": true } option:
Open in Playground
/*eslint accessor-pairs: "error"*/
var o = {
set a(value) {
this.val = value;
}
};
var o = {d: 1};
Object.defineProperty(o, 'c', {
set: function(value) {
this.val = value;
}
});
Examples of correct code for the default { "setWithoutGet": true } option:
Open in Playground
/*eslint accessor-pairs: "error"*/
var o = {
set a(value) {
this.val = value;
},
get a() {
return this.val;
}
};
var o = {d: 1};
Object.defineProperty(o, 'c', {
set: function(value) {
this.val = value;
},
get: function() {
return this.val;
}
});
getWithoutSet
Examples of incorrect code for the { "getWithoutSet": true } option:
Open in Playground
/*eslint accessor-pairs: ["error", { "getWithoutSet": true }]*/
var o = {
set a(value) {
this.val = value;
}
};
var o = {
get a() {
return this.val;
}
};
var o = {d: 1};
Object.defineProperty(o, 'c', {
set: function(value) {
this.val = value;
}
});
var o = {d: 1};
Object.defineProperty(o, 'c', {
get: function() {
return this.val;
}
});
Examples of correct code for the { "getWithoutSet": true } option:
Open in Playground
/*eslint accessor-pairs: ["error", { "getWithoutSet": true }]*/
var o = {
set a(value) {
this.val = value;
},
get a() {
return this.val;
}
};
var o = {d: 1};
Object.defineProperty(o, 'c', {
set: function(value) {
this.val = value;
},
get: function() {
return this.val;
}
});
enforceForClassMembers
When enforceForClassMembers is set to true (default):
"getWithoutSet": truewill also warn for getters without setters in classes."setWithoutGet": truewill also warn for setters without getters in classes.
Examples of incorrect code for { "getWithoutSet": true, "enforceForClassMembers": true }:
Open in Playground
/*eslint accessor-pairs: ["error", { "getWithoutSet": true, "enforceForClassMembers": true }]*/
class Foo {
get a() {
return this.val;
}
}
class Bar {
static get a() {
return this.val;
}
}
const Baz = class {
get a() {
return this.val;
}
static set a(value) {
this.val = value;
}
}
Examples of incorrect code for { "setWithoutGet": true, "enforceForClassMembers": true }:
Open in Playground
/*eslint accessor-pairs: ["error", { "setWithoutGet": true, "enforceForClassMembers": true }]*/
class Foo {
set a(value) {
this.val = value;
}
}
const Bar = class {
static set a(value) {
this.val = value;
}
}
When enforceForClassMembers is set to false, this rule ignores classes.
Examples of correct code for { "getWithoutSet": true, "setWithoutGet": true, "enforceForClassMembers": false }:
Open in Playground
/*eslint accessor-pairs: ["error", {
"getWithoutSet": true, "setWithoutGet": true, "enforceForClassMembers": false
}]*/
class Foo {
get a() {
return this.val;
}
}
class Bar {
static set a(value) {
this.val = value;
}
}
const Baz = class {
static get a() {
return this.val;
}
}
const Quux = class {
set a(value) {
this.val = value;
}
}
Known Limitations
Due to the limits of static analysis, this rule does not account for possible side effects and in certain cases might not report a missing pair for a getter/setter that has a computed key, like in the following example:
/*eslint accessor-pairs: "error"*/
var a = 1;
// no warnings
var o = {
get [a++]() {
return this.val;
},
set [a++](value) {
this.val = value;
}
};
Also, this rule does not disallow duplicate keys in object literals and class definitions, and in certain cases with duplicate keys might not report a missing pair for a getter/setter, like in the following example:
/*eslint accessor-pairs: "error"*/
// no warnings
var o = {
get a() {
return this.val;
},
a: 1,
set a(value) {
this.val = value;
}
};
The code above creates an object with just a setter for the property "a".
See no-dupe-keys if you also want to disallow duplicate keys in object literals.
See no-dupe-class-members if you also want to disallow duplicate names in class definitions.
When Not To Use It
You can turn this rule off if you are not concerned with the simultaneous presence of setters and getters on objects.
Related Rules
Version
This rule was introduced in ESLint v0.22.0.
Further Reading