Disallow use of this/super before calling super() in constructors. (no-this-before-super)

The "extends": "eslint:recommended" property in a configuration file enables this rule.

In the constructor of derived classes, if this/super are used before super() calls, it raises a reference error.

This rule checks this/super keywords in constructors, then reports those that are before super().

Rule Details

This rule is aimed to flag this/super keywords before super() callings.

Examples

Examples of incorrect code for this rule:

/*eslint no-this-before-super: "error"*/
/*eslint-env es6*/

class A extends B {
    constructor() {
        this.a = 0;
        super();
    }
}

class A extends B {
    constructor() {
        this.foo();
        super();
    }
}

class A extends B {
    constructor() {
        super.foo();
        super();
    }
}

class A extends B {
    constructor() {
        super(this.foo());
    }
}

Examples of correct code for this rule:

/*eslint no-this-before-super: "error"*/
/*eslint-env es6*/

class A {
    constructor() {
        this.a = 0; // OK, this class doesn't have an `extends` clause.
    }
}

class A extends B {
    constructor() {
        super();
        this.a = 0; // OK, this is after `super()`.
    }
}

class A extends B {
    foo() {
        this.a = 0; // OK. this is not in a constructor.
    }
}

When Not To Use It

If you don’t want to be notified about using this/super before super() in constructors, you can safely disable this rule.

Version

This rule was introduced in ESLint 0.24.0.

Resources

• Rule source
• Documentation source