Skip to content

[ESLint] Warn about dependencies outside of render scope #14990

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Mar 1, 2019
Merged

[ESLint] Warn about dependencies outside of render scope #14990

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
174 changes: 160 additions & 14 deletions packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -592,15 +592,6 @@ const tests = {
}
`,
},
{
// It is valid for effects to over-specify their deps.
// TODO: maybe only allow local ones, and disallow this example.
code: `
function MyComponent() {
useEffect(() => {}, [window]);
}
`,
},
{
// It is valid for effects to over-specify their deps.
code: `
Expand Down Expand Up @@ -897,8 +888,6 @@ const tests = {
],
},
{
// TODO: this case is weird.
// Maybe it should not consider local1 unused despite component nesting?
code: `
function MyComponent() {
const local1 = {};
Expand All @@ -924,9 +913,10 @@ const tests = {
}
`,
errors: [
// Focus on the more important part first (missing dep)
"React Hook useCallback has a missing dependency: 'local2'. " +
'Either include it or remove the dependency array.',
'Either include it or remove the dependency array. ' +
"Values like 'local1' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
Expand Down Expand Up @@ -990,7 +980,9 @@ const tests = {
`,
errors: [
"React Hook useCallback has an unnecessary dependency: 'window'. " +
'Either exclude it or remove the dependency array.',
'Either exclude it or remove the dependency array. ' +
"Values like 'window' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
Expand Down Expand Up @@ -2530,6 +2522,160 @@ const tests = {
'Either include it or remove the dependency array.',
],
},
{
code: `
function MyComponent() {
useEffect(() => {
window.scrollTo(0, 0);
}, [window]);
}
`,
errors: [
"React Hook useEffect has an unnecessary dependency: 'window'. " +
'Either exclude it or remove the dependency array. ' +
"Values like 'window' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
code: `
import MutableStore from 'store';

function MyComponent() {
useEffect(() => {
console.log(MutableStore.hello);
}, [MutableStore.hello]);
}
`,
output: `
import MutableStore from 'store';

function MyComponent() {
useEffect(() => {
console.log(MutableStore.hello);
}, []);
}
`,
errors: [
"React Hook useEffect has an unnecessary dependency: 'MutableStore.hello'. " +
'Either exclude it or remove the dependency array. ' +
"Values like 'MutableStore.hello' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
code: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
useEffect(() => {
console.log(MutableStore.hello.world, props.foo, x, y, z, global.stuff);
}, [MutableStore.hello.world, props.foo, x, y, z, global.stuff]);
}
}
`,
output: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
useEffect(() => {
console.log(MutableStore.hello.world, props.foo, x, y, z, global.stuff);
}, [props.foo, x, y]);
}
}
`,
errors: [
'React Hook useEffect has unnecessary dependencies: ' +
"'MutableStore.hello.world', 'global.stuff', and 'z'. " +
'Either exclude them or remove the dependency array. ' +
"Values like 'MutableStore.hello.world' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
code: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
useEffect(() => {
// nothing
}, [MutableStore.hello.world, props.foo, x, y, z, global.stuff]);
}
}
`,
// The output should contain the ones that are inside a component
// since there are legit reasons to over-specify them for effects.
output: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
useEffect(() => {
// nothing
}, [props.foo, x, y]);
}
}
`,
errors: [
'React Hook useEffect has unnecessary dependencies: ' +
"'MutableStore.hello.world', 'global.stuff', and 'z'. " +
'Either exclude them or remove the dependency array. ' +
"Values like 'MutableStore.hello.world' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
{
code: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
const fn = useCallback(() => {
// nothing
}, [MutableStore.hello.world, props.foo, x, y, z, global.stuff]);
}
}
`,
output: `
import MutableStore from 'store';
let z = {};

function MyComponent(props) {
let x = props.foo;
{
let y = props.bar;
const fn = useCallback(() => {
// nothing
}, []);
}
}
`,
errors: [
'React Hook useCallback has unnecessary dependencies: ' +
"'MutableStore.hello.world', 'global.stuff', 'props.foo', 'x', 'y', and 'z'. " +
'Either exclude them or remove the dependency array. ' +
"Values like 'MutableStore.hello.world' aren't valid dependencies " +
"because their mutation doesn't re-render the component.",
],
},
],
};

Expand Down
30 changes: 29 additions & 1 deletion packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ export default {
// scope. We can't enforce this in a lint so we trust that all variables
// declared outside of pure scope are indeed frozen.
const pureScopes = new Set();
let componentScope = null;
{
let currentScope = scope.upper;
while (currentScope) {
Expand All @@ -101,6 +102,7 @@ export default {
if (!currentScope) {
return;
}
componentScope = currentScope;
}

// These are usually mistaken. Collect them.
Expand Down Expand Up @@ -224,6 +226,7 @@ export default {
);

const declaredDependencies = [];
const externalDependencies = new Set();
if (declaredDependenciesNode.type !== 'ArrayExpression') {
// If the declared dependencies are not an array expression then we
// can't verify that the user provided the correct dependencies. Tell
Expand Down Expand Up @@ -298,11 +301,24 @@ export default {
throw error;
}
}

let maybeID = declaredDependencyNode;
while (maybeID.type === 'MemberExpression') {
maybeID = maybeID.object;
}
const isDeclaredInComponent = !componentScope.through.some(
ref => ref.identifier === maybeID,
);

// Add the dependency to our declared dependency map.
declaredDependencies.push({
key: declaredDependency,
node: declaredDependencyNode,
});

if (!isDeclaredInComponent) {
externalDependencies.add(declaredDependency);
}
});
}

Expand Down Expand Up @@ -348,6 +364,7 @@ export default {
dependencies,
declaredDependencies,
optionalDependencies,
externalDependencies,
isEffect,
});

Expand All @@ -370,6 +387,7 @@ export default {
dependencies,
declaredDependencies: [], // Pretend we don't know
optionalDependencies,
externalDependencies,
isEffect,
}).suggestedDependencies;
}
Expand Down Expand Up @@ -423,6 +441,11 @@ export default {
extraWarning =
` Mutable values like '${badRef}' aren't valid dependencies ` +
"because their mutation doesn't re-render the component.";
} else if (externalDependencies.size > 0) {
const dep = Array.from(externalDependencies)[0];
extraWarning =
` Values like '${dep}' aren't valid dependencies ` +
`because their mutation doesn't re-render the component.`;
}
}

Expand Down Expand Up @@ -462,6 +485,7 @@ function collectRecommendations({
dependencies,
declaredDependencies,
optionalDependencies,
externalDependencies,
isEffect,
}) {
// Our primary data structure.
Expand Down Expand Up @@ -584,7 +608,11 @@ function collectRecommendations({
duplicateDependencies.add(key);
}
} else {
if (isEffect && !key.endsWith('.current')) {
if (
isEffect &&
!key.endsWith('.current') &&
!externalDependencies.has(key)
) {
// Effects are allowed extra "unnecessary" deps.
// Such as resetting scroll when ID changes.
// Consider them legit.
Expand Down