Use of incompletely initialized object¶
ID: js/incomplete-object-initialization
Kind: problem
Security severity:
Severity: error
Precision: high
Tags:
- quality
- reliability
- correctness
- language-features
Query suites:
- javascript-security-and-quality.qls
Click to see the query in the CodeQL repository
If a class extends another class, its constructor needs to call the super constructor before referencing this or accessing properties through super. Failure to do so will cause a runtime error.
Recommendation¶
Insert a super constructor call.
Example¶
In the following example, class A extends class B, but its constructor assigns to this.x without first invoking the super constructor, which will cause a runtime error.
class A extends B {
constructor() { this.x = 42; }
}
To prevent the error, a super constructor call should be inserted:
class A extends B {
constructor() { super(); this.x = 42; }
}
References¶
Mozilla Developer Network: Sub classing with extends.