constructor-super

Require super() calls in constructors

Constructors of derived classes must call super(). Constructors of non derived classes must not call super(). If this is not observed, the JavaScript engine will raise a runtime error.

This rule checks whether or not there is a valid super() call.

Rule Details

This rule is aimed to flag invalid/missing super() calls.

This is a syntax error because there is no extends clause in the class:

class A {
    constructor() {
        super();
    }
}
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Examples of incorrect code for this rule:

/*eslint constructor-super: "error"*/

class A extends B {
    constructor() { }  // Would throw a ReferenceError.
}

// Classes which inherits from a non constructor are always problems.
class C extends null {
    constructor() {
        super();  // Would throw a TypeError.
    }
}

class D extends null {
    constructor() { }  // Would throw a ReferenceError.
}
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Examples of correct code for this rule:

/*eslint constructor-super: "error"*/

class A {
    constructor() { }
}

class B extends C {
    constructor() {
        super();
    }
}
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When Not To Use It

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

Handled by TypeScript

It is safe to disable this rule when using TypeScript because TypeScript's compiler enforces this check.

Version

This rule was introduced in ESLint v0.24.0.

Resources

• Rule source
• Tests source