Showing 5,758 of 5,758 total issues
Do not use comma operator here because it can be easily misunderstood or lead to unintended bugs. Open
StoryId,
StoryKind,
StoryName,
StoryIdentifier,
ViewMode,
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Rule: ban-comma-operator
Disallows the comma operator to be used.
Read more about the comma operator here.
Rationale
Using the comma operator can create a potential for many non-obvious bugs or lead to misunderstanding of code.
Examples
foo((bar, baz)); // evaluates to 'foo(baz)' because of the extra parens - confusing and not obvious
switch (foo) {
case 1, 2: // equals 'case 2' - probably intended 'case 1: case2:'
return true;
case 3:
return false;
}
let x = (y = 1, z = 2); // x is equal to 2 - this may not be immediately obvious.
Examples
"ban-comma-operator": true
For more information see this page.
unused expression, expected an assignment or function call Open
import type { ProdCliOptions } from './prod';
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Rule: no-unused-expression
Disallows unused expression statements.
Unused expressions are expression statements which are not assignments or function calls (and thus usually no-ops).
Rationale
Detects potential errors where an assignment or function call was intended.
Config
Three arguments may be optionally provided:
-
allow-fast-null-checks
allows to use logical operators to perform fast null checks and perform method or function calls for side effects (e.g.e && e.preventDefault()
). -
allow-new
allows 'new' expressions for side effects (e.g.new ModifyGlobalState();
. -
allow-tagged-template
allows tagged templates for side effects (e.g.this.add\
foo`;`.
Examples
"no-unused-expression": true
"no-unused-expression": true,allow-fast-null-checks
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"allow-fast-null-checks",
"allow-new",
"allow-tagged-template"
]
},
"minLength": 0,
"maxLength": 3
}
For more information see this page.
Missing semicolon Open
import type { Options, StorybookConfig } from '@storybook/core-common';
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Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
" should be ' Open
<div className="App">
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Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
Multiple imports from '../lib/cli/src/repro-generators/configs' can be combined into one. Open
import { Parameters } from '../lib/cli/src/repro-generators/configs';
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Rule: no-duplicate-imports
Disallows multiple import statements from the same module.
Rationale
Using a single import statement per module will make the code clearer because you can see everything being imported from that module on one line.
Config
"allow-namespace-imports" allows you to import namespaces on separate lines.
Examples
"no-duplicate-imports": true,[object Object]
Schema
{
"type": "object",
"properties": {
"allow-namespace-imports": {
"type": "boolean"
}
}
}
For more information see this page.
Type assertion on object literals is forbidden, use a type annotation instead. Open
expect.objectContaining({
absoluteBaseUrl: expect.any(String),
} as TsconfigPathsPlugin),
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Rule: no-object-literal-type-assertion
Forbids an object literal to appear in a type assertion expression.
Casting to any
or to unknown
is still allowed.
Rationale
Always prefer const x: T = { ... };
to const x = { ... } as T;
.
The type assertion in the latter case is either unnecessary or hides an error.
The compiler will warn for excess properties with this syntax, but not missing required fields.
For example: const x: { foo: number } = {}
will fail to compile, but
const x = {} as { foo: number }
will succeed.
Additionally, the const assertion const x = { foo: 1 } as const
,
introduced in TypeScript 3.4, is considered beneficial and is ignored by this rule.
Notes
- TypeScript Only
Config
One option may be configured:
-
allow-arguments
allows type assertions to be used on object literals inside call expressions.
Examples
"no-object-literal-type-assertion": true
"no-object-literal-type-assertion": true,[object Object]
Schema
{
"type": "object",
"properties": {
"allow-arguments": {
"type": "boolean"
}
},
"additionalProperties": false
}
For more information see this page.
Type assertion on object literals is forbidden, use a type annotation instead. Open
options = { angularBrowserTarget: 'target-project:target-build' } as PresetOptions;
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Rule: no-object-literal-type-assertion
Forbids an object literal to appear in a type assertion expression.
Casting to any
or to unknown
is still allowed.
Rationale
Always prefer const x: T = { ... };
to const x = { ... } as T;
.
The type assertion in the latter case is either unnecessary or hides an error.
The compiler will warn for excess properties with this syntax, but not missing required fields.
For example: const x: { foo: number } = {}
will fail to compile, but
const x = {} as { foo: number }
will succeed.
Additionally, the const assertion const x = { foo: 1 } as const
,
introduced in TypeScript 3.4, is considered beneficial and is ignored by this rule.
Notes
- TypeScript Only
Config
One option may be configured:
-
allow-arguments
allows type assertions to be used on object literals inside call expressions.
Examples
"no-object-literal-type-assertion": true
"no-object-literal-type-assertion": true,[object Object]
Schema
{
"type": "object",
"properties": {
"allow-arguments": {
"type": "boolean"
}
},
"additionalProperties": false
}
For more information see this page.
unused expression, expected an assignment or function call Open
import type { ProdCliOptions } from './prod';
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Rule: no-unused-expression
Disallows unused expression statements.
Unused expressions are expression statements which are not assignments or function calls (and thus usually no-ops).
Rationale
Detects potential errors where an assignment or function call was intended.
Config
Three arguments may be optionally provided:
-
allow-fast-null-checks
allows to use logical operators to perform fast null checks and perform method or function calls for side effects (e.g.e && e.preventDefault()
). -
allow-new
allows 'new' expressions for side effects (e.g.new ModifyGlobalState();
. -
allow-tagged-template
allows tagged templates for side effects (e.g.this.add\
foo`;`.
Examples
"no-unused-expression": true
"no-unused-expression": true,allow-fast-null-checks
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"allow-fast-null-checks",
"allow-new",
"allow-tagged-template"
]
},
"minLength": 0,
"maxLength": 3
}
For more information see this page.
Missing semicolon Open
import type { Parameters } from '@storybook/addons';
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Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
Missing semicolon Open
import type { ProdCliOptions } from './prod';
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Rule: semicolon
Enforces consistent semicolon usage at the end of every statement.
Notes
- Has Fix
Config
One of the following arguments must be provided:
-
"always"
enforces semicolons at the end of every statement. -
"never"
disallows semicolons at the end of every statement except for when they are necessary.
The following arguments may be optionally provided:
-
"ignore-interfaces"
skips checking semicolons at the end of interface members. -
"ignore-bound-class-methods"
skips checking semicolons at the end of bound class methods. -
"strict-bound-class-methods"
disables any special handling of bound class methods and treats them as any other assignment. This option overrides"ignore-bound-class-methods"
.
Examples
"semicolon": true,always
"semicolon": true,never
"semicolon": true,always,ignore-interfaces
"semicolon": true,always,ignore-bound-class-methods
Schema
{
"type": "array",
"items": [
{
"type": "string",
"enum": [
"always",
"never"
]
},
{
"type": "string",
"enum": [
"ignore-interfaces"
]
}
],
"additionalItems": false
}
For more information see this page.
Shadowed name: 'main' Open
const checkInstalled = (addon: string, main: any) => {
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Rule: no-shadowed-variable
Disallows shadowing variable declarations.
Rationale
When a variable in a local scope and a variable in the containing scope have the same name, shadowing occurs. Shadowing makes it impossible to access the variable in the containing scope and obscures to what value an identifier actually refers. Compare the following snippets:
const a = 'no shadow';
function print() {
console.log(a);
}
print(); // logs 'no shadow'.
const a = 'no shadow';
function print() {
const a = 'shadow'; // TSLint will complain here.
console.log(a);
}
print(); // logs 'shadow'.
ESLint has an equivalent rule. For more background information, refer to this MDN closure doc.
Config
You can optionally pass an object to disable checking for certain kinds of declarations.
Possible keys are "class"
, "enum"
, "function"
, "import"
, "interface"
, "namespace"
, "typeAlias"
and "typeParameter"
. You can also pass "underscore
" to ignore variable names that begin with _
.
Just set the value to false
for the check you want to disable.
All checks default to true
, i.e. are enabled by default.
Note that you cannot disable variables and parameters.
The option "temporalDeadZone"
defaults to true
which shows errors when shadowing block scoped declarations in their
temporal dead zone. When set to false
parameters, classes, enums and variables declared
with let
or const
are not considered shadowed if the shadowing occurs within their
temporal dead zone.
The following example shows how the "temporalDeadZone"
option changes the linting result:
function fn(value) {
if (value) {
const tmp = value; // no error on this line if "temporalDeadZone" is false
return tmp;
}
let tmp = undefined;
if (!value) {
const tmp = value; // this line always contains an error
return tmp;
}
}
Examples
"no-shadowed-variable": true
"no-shadowed-variable": true,[object Object]
Schema
{
"type": "object",
"properties": {
"class": {
"type": "boolean"
},
"enum": {
"type": "boolean"
},
"function": {
"type": "boolean"
},
"import": {
"type": "boolean"
},
"interface": {
"type": "boolean"
},
"namespace": {
"type": "boolean"
},
"typeAlias": {
"type": "boolean"
},
"typeParameter": {
"type": "boolean"
},
"temporalDeadZone": {
"type": "boolean"
},
"underscore": {
"type": "boolean"
}
}
}
For more information see this page.
" should be ' Open
['root directory /', '/', "Won't remove directory '/'. Check your outputDir!"],
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- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
" should be ' Open
<SyntaxHighlighter language="bash" copyable padded bordered>
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Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
" should be ' Open
<NotificationClearer api={api} notificationId="update">
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
Type assertion on object literals is forbidden, use a type annotation instead. Open
clientApi.storiesOf('Component A', { id: 'file1' } as NodeModule).add('story0', jest.fn());
- Read upRead up
- Exclude checks
Rule: no-object-literal-type-assertion
Forbids an object literal to appear in a type assertion expression.
Casting to any
or to unknown
is still allowed.
Rationale
Always prefer const x: T = { ... };
to const x = { ... } as T;
.
The type assertion in the latter case is either unnecessary or hides an error.
The compiler will warn for excess properties with this syntax, but not missing required fields.
For example: const x: { foo: number } = {}
will fail to compile, but
const x = {} as { foo: number }
will succeed.
Additionally, the const assertion const x = { foo: 1 } as const
,
introduced in TypeScript 3.4, is considered beneficial and is ignored by this rule.
Notes
- TypeScript Only
Config
One option may be configured:
-
allow-arguments
allows type assertions to be used on object literals inside call expressions.
Examples
"no-object-literal-type-assertion": true
"no-object-literal-type-assertion": true,[object Object]
Schema
{
"type": "object",
"properties": {
"allow-arguments": {
"type": "boolean"
}
},
"additionalProperties": false
}
For more information see this page.
" should be ' Open
<Link secondary href="https://github.com/storybookjs/storybook" cancel={false} target="_blank">
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
" should be ' Open
<header className="App-header">
- Read upRead up
- Exclude checks
Rule: quotemark
Enforces quote character for string literals.
Notes
- Has Fix
Config
Five arguments may be optionally provided:
-
"single"
enforces single quotes. -
"double"
enforces double quotes. -
"backtick"
enforces backticks. -
"jsx-single"
enforces single quotes for JSX attributes. -
"jsx-double"
enforces double quotes for JSX attributes. -
"avoid-template"
forbids single-line untagged template strings that do not contain string interpolations. Note that backticks may still be used if"avoid-escape"
is enabled and both single and double quotes are present in the string (the latter option takes precedence). -
"avoid-escape"
allows you to use the "other" quotemark in cases where escaping would normally be required. For example,[true, "double", "avoid-escape"]
would not report a failure on the string literal'Hello "World"'
.
Examples
"quotemark": true,single,avoid-escape,avoid-template
"quotemark": true,single,jsx-double
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"single",
"double",
"backtick",
"jsx-single",
"jsx-double",
"avoid-escape",
"avoid-template"
]
},
"minLength": 0,
"maxLength": 5
}
For more information see this page.
block is empty Open
navigate={() => {}}
- Read upRead up
- Exclude checks
Rule: no-empty
Disallows empty blocks.
Blocks with a comment inside are not considered empty.
Rationale
Empty blocks are often indicators of missing code.
Config
If allow-empty-catch
is specified, then catch blocks are allowed to be empty.
If allow-empty-functions
is specified, then function definitions are allowed to be empty.
Examples
"no-empty": true
"no-empty": true,allow-empty-catch
"no-empty": true,allow-empty-functions
"no-empty": true,allow-empty-catch,allow-empty-functions
Schema
{
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"enum": [
"allow-empty-catch"
]
},
{
"type": "string",
"enum": [
"allow-empty-functions"
]
}
]
}
}
For more information see this page.
unused expression, expected an assignment or function call Open
import type { StorybookConfig } from '@storybook/core-common';
- Read upRead up
- Exclude checks
Rule: no-unused-expression
Disallows unused expression statements.
Unused expressions are expression statements which are not assignments or function calls (and thus usually no-ops).
Rationale
Detects potential errors where an assignment or function call was intended.
Config
Three arguments may be optionally provided:
-
allow-fast-null-checks
allows to use logical operators to perform fast null checks and perform method or function calls for side effects (e.g.e && e.preventDefault()
). -
allow-new
allows 'new' expressions for side effects (e.g.new ModifyGlobalState();
. -
allow-tagged-template
allows tagged templates for side effects (e.g.this.add\
foo`;`.
Examples
"no-unused-expression": true
"no-unused-expression": true,allow-fast-null-checks
Schema
{
"type": "array",
"items": {
"type": "string",
"enum": [
"allow-fast-null-checks",
"allow-new",
"allow-tagged-template"
]
},
"minLength": 0,
"maxLength": 3
}
For more information see this page.
Don't use 'Function' as a type. Avoid using the Function
type. Prefer a specific function type, like () => void
. Open
resolvers: Record<Call['id'], Function>;
- Read upRead up
- Exclude checks
Rule: ban-types
Bans specific types from being used. Does not ban the corresponding runtime objects from being used.
Notes
- TypeScript Only
Config
A list of ["regex", "optional explanation here"]
, which bans
types that match regex
Examples
"ban-types": true,Object,Use {} instead.,String
Schema
{
"type": "list",
"listType": {
"type": "array",
"items": {
"type": "string"
},
"minLength": 1,
"maxLength": 2
}
}
For more information see this page.