useFlatMap
Summary
Section titled “Summary”- Rule available since:
v1.0.0 - Diagnostic Category:
lint/complexity/useFlatMap - This rule is recommended, meaning it is enabled by default.
- This rule has a safe fix.
- The default severity of this rule is information.
- Sources:
- Same as
unicorn/prefer-array-flat-map - Same as
map_flatten
- Same as
How to configure
Section titled “How to configure”{ "linter": { "rules": { "complexity": { "useFlatMap": "error" } } }}Description
Section titled “Description”Promotes the use of .flatMap() when map().flat() are used together.
Using .flatMap() instead of map().flat() avoids the creation of
an intermediate array.
Examples
Section titled “Examples”Invalid
Section titled “Invalid”const array = ["split", "the text", "into words"];array.map(sentence => sentence.split(' ')).flat();code-block.js:2:1 lint/complexity/useFlatMap FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ The call chain .map().flat() can be replaced with a single .flatMap() call.
1 │ const array = [“split”, “the text”, “into words”];
> 2 │ array.map(sentence => sentence.split(’ ‘)).flat();
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3 │
ℹ Using .flatMap() avoids the creation of an intermediate array.
ℹ Safe fix: Replace the chain with .flatMap().
1 1 │ const array = [“split”, “the text”, “into words”];
2 │ - array.map(sentence·=>·sentence.split(’·‘)).flat();
2 │ + array.flatMap(sentence·=>·sentence.split(’·’));
3 3 │
const array = ["split", "the text", "into words"];array.map(sentence => sentence.split(' ')).flat(1);code-block.js:2:1 lint/complexity/useFlatMap FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ The call chain .map().flat() can be replaced with a single .flatMap() call.
1 │ const array = [“split”, “the text”, “into words”];
> 2 │ array.map(sentence => sentence.split(’ ‘)).flat(1);
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3 │
ℹ Using .flatMap() avoids the creation of an intermediate array.
ℹ Safe fix: Replace the chain with .flatMap().
1 1 │ const array = [“split”, “the text”, “into words”];
2 │ - array.map(sentence·=>·sentence.split(’·‘)).flat(1);
2 │ + array.flatMap(sentence·=>·sentence.split(’·’));
3 3 │
const array = ["split", "the text", "into words"];array.map(sentence => sentence.split(' ')).flat(2);Related links
Section titled “Related links”Sponsored by
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