no-constructor-return

Disallow returning value from constructor

In JavaScript, returning a value in the constructor of a class may be a mistake. Forbidding this pattern prevents mistakes resulting from unfamiliarity with the language or a copy-paste error.

Rule Details

This rule disallows return statements in the constructor of a class. Note that returning nothing is allowed.

Examples of incorrect code for this rule:

/*eslint no-constructor-return: "error"*/

class A {
    constructor(a) {
        this.a = a;
        return a;
    }
}

class B {
    constructor(f) {
        if (!f) {
            return 'falsy';
        }
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

Examples of correct code for this rule:

/*eslint no-constructor-return: "error"*/

class C {
    constructor(c) {
        this.c = c;
    }
}

class D {
    constructor(f) {
        if (!f) {
            return;  // Flow control.
        }

        f();
    }
}

class E {
    constructor() {
        return;
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

Version

This rule was introduced in ESLint v6.7.0.

Resources

• Rule source
• Tests source