Should not have unused variables JS-0128
Bug risk
2 months ago
—
8 months old
'props' is defined but never used. Allowed unused args must match /^_/u
3import { Checkbox, Divider } from 'semantic-ui-react';
4import { VideoPreview } from '../../VideoPreview/VideoPreview';
5
6const NextUpVideo = props => ( 7 <Fragment>
8 <div className="nextup-container">
9 <h4>Up next</h4>'props' is defined but never used. Allowed unused args must match /^_/u
3import { VideoPreview } from '../VideoPreview/VideoPreview';
4import NextUpVideo from './NextUpVideo/NextUpVideo';
5
6const RelatedVideos = props => ( 7 <div className="related-videos">
8 <NextUpVideo />
9 <VideoPreview horizontal />'props' is defined but never used. Allowed unused args must match /^_/u
3import { Button, Image } from 'semantic-ui-react';
4import Rating from '../../../components/Rating/Rating';
5
6const Comment = props => ( 7 <div className="comment">
8 <Image className="user-image" src="https://via.placeholder.com/48x48" circular />
9 <div>'props' is defined but never used. Allowed unused args must match /^_/u
3import SideBarHeader from '../SideBarHeader/SideBarHeader';
4import Subscription from './Subscription/Subscription';
5
6const Subscriptions = props => ( 7 <Fragment>
8 <SideBarHeader title="subscriptions" />
9 <Subscription label="MusicChannel" broadcasting />'React' is defined but never used. Allowed unused vars must match /^_/u
3// // expect(element).toHaveTextContent(/react/i)
4// // learn more: https://github.com/testing-library/jest-dom
5// import '@testing-library/jest-dom/extend-expect';
6import React from 'react'; 7import Enzyme from 'enzyme';
8import Adapter from 'enzyme-adapter-react-16';
9import {createSerializer} from 'enzyme-to-json';
Description
Found variables that are declared but not used anywhere.
NOTE: In browser applications, DeepSource recommends the use of ESModules over regular
text/javascriptscripts. Currently, we don't support variables that are not explicitly exported, and are injected into other scripts by being included in an HTML file
Unused variables are most often the result of incomplete refactoring. They can lead to confusing code and minor performance hitches.
NOTE: If you have intentionally left a variable unused, we suggest you to prefix the variable name with a _ to prevent them from being flagged by DeepSource.
Bad Practice
// Write-only variables are not considered as used.
let y = 10;
y = 5;
// A variable that modifies only itself isn't considered used.
let z = 0;
z = z + 1;
// Unused argument
(function(x) {
return 5;
})();
// Unused recursive functions also raise this issue.
function fact(n) {
if (n < 2) return 1;
return n * fact(n - 1);
}
// When a function definition destructures an array,
// unused entries from the array also cause warnings.
function getY([x, y]) {
return y;
}
Recommended
let x = 10;
alert(x);
((arg1) => {
return arg1;
})();
let myFunc;
myFunc = (n) => {
// this is legal
if (n < 0) myFunc();
};
// this is also considered legal
console.log(declaredLater);
var declaredLater;
// Only the second argument from the descructured array is used.
function getY([, y]) {
return y;
}