Expected to return a value at the end of arrow function. Open
renderPrecentage = (index) => {
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require return
statements to either always or never specify values (consistent-return)
Unlike statically-typed languages which enforce that a function returns a specified type of value, JavaScript allows different code paths in a function to return different types of values.
A confusing aspect of JavaScript is that a function returns undefined
if any of the following are true:
- it does not execute a
return
statement before it exits - it executes
return
which does not specify a value explicitly - it executes
return undefined
- it executes
return void
followed by an expression (for example, a function call) - it executes
return
followed by any other expression which evaluates toundefined
If any code paths in a function return a value explicitly but some code path do not return a value explicitly, it might be a typing mistake, especially in a large function. In the following example:
- a code path through the function returns a Boolean value
true
- another code path does not return a value explicitly, therefore returns
undefined
implicitly
function doSomething(condition) {
if (condition) {
return true;
} else {
return;
}
}
Rule Details
This rule requires return
statements to either always or never specify values. This rule ignores function definitions where the name begins with an uppercase letter, because constructors (when invoked with the new
operator) return the instantiated object implicitly if they do not return another object explicitly.
Examples of incorrect code for this rule:
/*eslint consistent-return: "error"*/
function doSomething(condition) {
if (condition) {
return true;
} else {
return;
}
}
function doSomething(condition) {
if (condition) {
return true;
}
}
Examples of correct code for this rule:
/*eslint consistent-return: "error"*/
function doSomething(condition) {
if (condition) {
return true;
} else {
return false;
}
}
function Foo() {
if (!(this instanceof Foo)) {
return new Foo();
}
this.a = 0;
}
Options
This rule has an object option:
-
"treatUndefinedAsUnspecified": false
(default) always either specify values or returnundefined
implicitly only. -
"treatUndefinedAsUnspecified": true
always either specify values or returnundefined
explicitly or implicitly.
treatUndefinedAsUnspecified
Examples of incorrect code for this rule with the default { "treatUndefinedAsUnspecified": false }
option:
/*eslint consistent-return: ["error", { "treatUndefinedAsUnspecified": false }]*/
function foo(callback) {
if (callback) {
return void callback();
}
// no return statement
}
function bar(condition) {
if (condition) {
return undefined;
}
// no return statement
}
Examples of incorrect code for this rule with the { "treatUndefinedAsUnspecified": true }
option:
/*eslint consistent-return: ["error", { "treatUndefinedAsUnspecified": true }]*/
function foo(callback) {
if (callback) {
return void callback();
}
return true;
}
function bar(condition) {
if (condition) {
return undefined;
}
return true;
}
Examples of correct code for this rule with the { "treatUndefinedAsUnspecified": true }
option:
/*eslint consistent-return: ["error", { "treatUndefinedAsUnspecified": true }]*/
function foo(callback) {
if (callback) {
return void callback();
}
// no return statement
}
function bar(condition) {
if (condition) {
return undefined;
}
// no return statement
}
When Not To Use It
If you want to allow functions to have different return
behavior depending on code branching, then it is safe to disable this rule.
Source: http://eslint.org/docs/rules/
Unexpected block statement surrounding arrow body. Open
<div className="column" onTouchStart={(event) => {
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Require braces in arrow function body (arrow-body-style)
Arrow functions have two syntactic forms for their function bodies. They may be defined with a block body (denoted by curly braces) () => { ... }
or with a single expression () => ...
, whose value is implicitly returned.
Rule Details
This rule can enforce or disallow the use of braces around arrow function body.
Options
The rule takes one or two options. The first is a string, which can be:
-
"always"
enforces braces around the function body -
"as-needed"
enforces no braces where they can be omitted (default) -
"never"
enforces no braces around the function body (constrains arrow functions to the role of returning an expression)
The second one is an object for more fine-grained configuration when the first option is "as-needed"
. Currently, the only available option is requireReturnForObjectLiteral
, a boolean property. It's false
by default. If set to true
, it requires braces and an explicit return for object literals.
"arrow-body-style": ["error", "always"]
always
Examples of incorrect code for this rule with the "always"
option:
/*eslint arrow-body-style: ["error", "always"]*/
/*eslint-env es6*/
let foo = () => 0;
Examples of correct code for this rule with the "always"
option:
let foo = () => {
return 0;
};
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
as-needed
Examples of incorrect code for this rule with the default "as-needed"
option:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => {
return 0;
};
let foo = () => {
return {
bar: {
foo: 1,
bar: 2,
}
};
};
Examples of correct code for this rule with the default "as-needed"
option:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => 0;
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
let foo = () => ({
bar: {
foo: 1,
bar: 2,
}
});
let foo = () => { bar(); };
let foo = () => {};
let foo = () => { /* do nothing */ };
let foo = () => {
// do nothing.
};
let foo = () => ({ bar: 0 });
requireReturnForObjectLiteral
This option is only applicable when used in conjunction with the
"as-needed"
option.
Examples of incorrect code for this rule with the { "requireReturnForObjectLiteral": true }
option:
/*eslint arrow-body-style: ["error", "as-needed", { "requireReturnForObjectLiteral": true }]*/
/*eslint-env es6*/
let foo = () => ({});
let foo = () => ({ bar: 0 });
Examples of correct code for this rule with the { "requireReturnForObjectLiteral": true }
option:
/*eslint arrow-body-style: ["error", "as-needed", { "requireReturnForObjectLiteral": true }]*/
/*eslint-env es6*/
let foo = () => {};
let foo = () => { return { bar: 0 }; };
never
Examples of incorrect code for this rule with the "never"
option:
/*eslint arrow-body-style: ["error", "never"]*/
/*eslint-env es6*/
let foo = () => {
return 0;
};
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
Examples of correct code for this rule with the "never"
option:
/*eslint arrow-body-style: ["error", "never"]*/
/*eslint-env es6*/
let foo = () => 0;
let foo = () => ({ foo: 0 });
Source: http://eslint.org/docs/rules/
Useless constructor. Open
constructor (props) {
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Disallow unnecessary constructor (no-useless-constructor)
ES2015 provides a default class constructor if one is not specified. As such, it is unnecessary to provide an empty constructor or one that simply delegates into its parent class, as in the following examples:
class A {
constructor () {
}
}
class A extends B {
constructor (value) {
super(value);
}
}
Rule Details
This rule flags class constructors that can be safely removed without changing how the class works.
Examples
Examples of incorrect code for this rule:
/*eslint no-useless-constructor: "error"*/
/*eslint-env es6*/
class A {
constructor () {
}
}
class A extends B {
constructor (...args) {
super(...args);
}
}
Examples of correct code for this rule:
/*eslint no-useless-constructor: "error"*/
class A { }
class A {
constructor () {
doSomething();
}
}
class A extends B {
constructor() {
super('foo');
}
}
class A extends B {
constructor() {
super();
doSomething();
}
}
When Not To Use It
If you don't want to be notified about unnecessary constructors, you can safely disable this rule. Source: http://eslint.org/docs/rules/
Similar blocks of code found in 3 locations. Consider refactoring. Open
static propTypes = {
index: PropTypes.number.isRequired,
upload: PropTypes.object.isRequired,
src: PropTypes.string.isRequired,
dispatch: PropTypes.func.isRequired,
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Duplicated Code
Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:
Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.
When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).
Tuning
This issue has a mass of 84.
We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.
The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.
If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.
See codeclimate-duplication
's documentation for more information about tuning the mass threshold in your .codeclimate.yml
.
Refactorings
- Extract Method
- Extract Class
- Form Template Method
- Introduce Null Object
- Pull Up Method
- Pull Up Field
- Substitute Algorithm
Further Reading
- Don't Repeat Yourself on the C2 Wiki
- Duplicated Code on SourceMaking
- Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76
Prop type object
is forbidden Open
upload: PropTypes.object.isRequired,
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For more information visit Source: http://eslint.org/docs/rules/
The closing bracket must be aligned with the line containing the opening tag (expected column 9 on the next line) Open
className="ui blue percentage message">
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For more information visit Source: http://eslint.org/docs/rules/
Prop type object
is forbidden Open
post: PropTypes.object.isRequired
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For more information visit Source: http://eslint.org/docs/rules/
There should be no space before '}' Open
} }>
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For more information visit Source: http://eslint.org/docs/rules/
The closing bracket must be aligned with the line containing the opening tag (expected column 9 on the next line) Open
onDrop={this.handleDrop}>
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The closing bracket must be aligned with the line containing the opening tag (expected column 11 on the next line) Open
className="ui green percentage message">
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For more information visit Source: http://eslint.org/docs/rules/
Using this.refs is deprecated. Open
return this.refs.dropzone.open()
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For more information visit Source: http://eslint.org/docs/rules/
Property should be placed on a new line Open
<div className="column" onTouchStart={(event) => {
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For more information visit Source: http://eslint.org/docs/rules/
The closing bracket must be aligned with the line containing the opening tag (expected column 7 on the next line) Open
} }>
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For more information visit Source: http://eslint.org/docs/rules/
The closing bracket must be aligned with the line containing the opening tag (expected column 11 on the next line) Open
src={ imgsrc || this.props.src } />
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For more information visit Source: http://eslint.org/docs/rules/
JSX props should not use .bind() Open
<button className="fluid ui red button percentage message" onClick={this.handleDelete.bind(this, index)}>{_T('post.detail.delete.confirm')}</button>
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The closing bracket must be aligned with the line containing the opening tag (expected column 9 on the next line) Open
className="ui yellow percentage message">
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For more information visit Source: http://eslint.org/docs/rules/
There should be no space after '{' Open
src={ imgsrc || this.props.src } />
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For more information visit Source: http://eslint.org/docs/rules/
Using string literals in ref attributes is deprecated. Open
ref="dropzone"
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For more information visit Source: http://eslint.org/docs/rules/
There should be no space before '}' Open
src={ imgsrc || this.props.src } />
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For more information visit Source: http://eslint.org/docs/rules/
JSX not allowed in files with extension '.js' Open
<button className="fluid ui red button percentage message" onClick={this.handleDelete.bind(this, index)}>{_T('post.detail.delete.confirm')}</button>
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For more information visit Source: http://eslint.org/docs/rules/