typescript/prefer-optional-chain Nursery
What it does
Enforce using concise optional chain expressions instead of chained logical AND operators, negated logical OR operators, or empty objects.
Note that this rule is in the nursery category while we ensure it is working correctly in as many edge-case scenarios as possible. The logic for this is complex and the autofix may cause logic changes in some edge-cases.
Why is this bad?
TypeScript 3.7 introduced optional chaining (?.) which provides a more concise and readable way to access properties on potentially nullish values. Using optional chaining instead of logical AND chains (&&) or other patterns improves code clarity.
Examples
Examples of incorrect code for this rule:
foo && foo.bar;
foo && foo.bar && foo.bar.baz;
foo && foo["bar"];
foo && foo.bar && foo.bar.baz && foo.bar.baz.buzz;
foo && foo.bar && foo.bar.baz.buzz;
foo && foo.bar.baz && foo.bar.baz.buzz;
(foo || {}).bar;Examples of correct code for this rule:
foo?.bar;
foo?.bar?.baz;
foo?.["bar"];
foo?.bar?.baz?.buzz;
foo?.bar?.baz.buzz;
foo?.bar.baz?.buzz;
foo?.bar;Configuration
This rule accepts a configuration object with the following properties:
allowPotentiallyUnsafeFixesThatModifyTheReturnTypeIKnowWhatImDoing
type: boolean
default: false
Allow autofixers that will change the return type of the expression. This option is considered unsafe as it may break the build.
checkAny
type: boolean
default: true
Check operands that are typed as any when inspecting "loose boolean" operands.
checkBigInt
type: boolean
default: true
Check operands that are typed as bigint when inspecting "loose boolean" operands.
checkBoolean
type: boolean
default: true
Check operands that are typed as boolean when inspecting "loose boolean" operands.
checkNumber
type: boolean
default: true
Check operands that are typed as number when inspecting "loose boolean" operands.
checkString
type: boolean
default: true
Check operands that are typed as string when inspecting "loose boolean" operands.
checkUnknown
type: boolean
default: true
Check operands that are typed as unknown when inspecting "loose boolean" operands.
requireNullish
type: boolean
default: false
Skip operands that are not typed with null and/or undefined when inspecting "loose boolean" operands.
How to use
To enable this rule using the config file or in the CLI, you can use:
{
"options": {
"typeAware": true
},
"rules": {
"typescript/prefer-optional-chain": "error"
}
}import { defineConfig } from "oxlint";
export default defineConfig({
options: { typeAware: true },
rules: {
"typescript/prefer-optional-chain": "error",
},
});oxlint --type-aware --deny typescript/prefer-optional-chainVersion
This rule was added in v1.39.0.