When using Typescript with "strict": true in the tsconfig.json, a common issue arises where warnings are not triggered for potentially undefined properties, as shown by this code snippet:
let x: any = { test: false }
let y = x.asdf // no warning issued here
While the above code may still work, similar situations can lead to crashes, such as:
let x: any = { test: false }
let y = x.asdf.jjj // TypeError: Cannot read property 'jjj' of undefined
To address this issue and receive warnings for potential undefined properties, developers may consider utilizing a linter. This would help in proactively identifying situations where properties may be accessed without first verifying their existence.
For example:
let x = notDeclared
would indicate that notDeclared is not found within the scope.
UPDATE
Based on feedback from various sources, it has become evident that the aforementioned code examples only scratch the surface of the problem. The real challenge lies in scenarios where the structure of the x-object is unknown. For instance:
let x = JSON.parse(...) // the result is any
In cases like these, it becomes difficult to predict what properties the parsed object contains. A linter or similar tool could prove invaluable in delivering alerts when attempting to access potentially undefined properties, preventing catastrophic failures in the application due to overlooked issues.