49 lines
1.2 KiB
Plaintext
49 lines
1.2 KiB
Plaintext
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Disallow the use of optional chaining in an expression where the `undefined` value would raise an error.
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== Why is this an issue?
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The optional chaining operator `?.` allows to access a deeply nested property, returning `undefined` if the property or any intermediate object is `undefined`.
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This usually means that we expect the expression to evaluate as `undefined` in some cases. Therefore, using the optional chaining operator in a context where returning `undefined` is forbidden can lead to errors.
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=== What is the potential impact?
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Since optional chaining represents multiple execution branches, having an error thrown in such a context can be hard to debug.
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== How to fix it
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You should provide fallbacks for when the optional chaining operator is used to avoid runtime errors.
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=== Code examples
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==== Noncompliant code example
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[source,javascript]
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----
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new (foo?.bar)();
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const { foo } = bar?.baz;
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const foo = [...bar?.baz]
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----
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==== Compliant solution
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[source,javascript]
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----
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new (foo?.bar ?? baz)()
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const { foo } = bar?.baz || {}
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const foo = bar?.baz ? [...bar.baz] : []
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----
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//=== How does this work?
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//=== Pitfalls
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//=== Going the extra mile
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//== Resources
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//=== Documentation
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//=== Articles & blog posts
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//=== Conference presentations
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//=== Standards
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