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Enforces getter/setter pairs in objects (accessor-pairs)

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.

Options

  • setWithoutGet set to true will warn for setters without getters (Default true).
  • getWithoutSet set to true will warn for getters without setters (Default false).

setWithoutGet

Examples of incorrect code for the default { "setWithoutGet": true } option:

/*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:

/*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:

/*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:

/*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;
    }
});

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 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.

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.

Further Reading