unnecessary use of conditional expression for default assignment eslint

no-unneeded-ternary

Disallow ternary operators when simpler alternatives exist

Some problems reported by this rule are automatically fixable by the --fix command line option

It’s a common mistake in JavaScript to use a conditional expression to select between two Boolean values instead of using ! to convert the test to a Boolean. Here are some examples:

Another common mistake is using a single variable as both the conditional test and the consequent. In such cases, the logical OR can be used to provide the same functionality. Here is an example:

Rule Details

This rule disallow ternary operators when simpler alternatives exist.

Examples of incorrect code for this rule:

Examples of correct code for this rule:

This rule has an object option:

• "defaultAssignment": true (default) allows the conditional expression as a default assignment pattern
• "defaultAssignment": false disallows the conditional expression as a default assignment pattern

defaultAssignment

When set to true , which it is by default, The defaultAssignment option allows expressions of the form x ? x : expr (where x is any identifier and expr is any expression).

Examples of additional incorrect code for this rule with the { "defaultAssignment": false } option:

Note that defaultAssignment: false still allows expressions of the form x ? expr : x (where the identifier is on the right hand side of the ternary).

When Not To Use It

You can turn this rule off if you are not concerned with unnecessary complexity in conditional expressions.

Related Rules

• no-nested-ternary

This rule was introduced in ESLint v0.21.0.

• Rule source
• Tests source

© OpenJS Foundation and other contributors Licensed under the MIT License. https://eslint.org/docs/latest/rules/no-unneeded-ternary

no-unnecessary-condition

Disallow conditionals where the type is always truthy or always falsy.

Extending "plugin:@typescript-eslint/ strict-type-checked " in an ESLint configuration enables this rule.

Some problems reported by this rule are automatically fixable by the --fix ESLint command line option .

This rule requires type information to run.

Any expression being used as a condition must be able to evaluate as truthy or falsy in order to be considered "necessary". Conversely, any expression that always evaluates to truthy or always evaluates to falsy, as determined by the type of the expression, is considered unnecessary and will be flagged by this rule.

The following expressions are checked:

• Arguments to the && , || and ?: (ternary) operators
• Conditions for if , for , while , and do-while statements
• Base values of optional chain expressions

Try this rule in the playground ↗

• ❌ Incorrect

This rule accepts the following options:

allowConstantLoopConditions ​

Example of correct code for { allowConstantLoopConditions: true } :

allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing ​

If this is set to false , then the rule will error on every file whose tsconfig.json does not have the strictNullChecks compiler option (or strict ) set to true .

Without strictNullChecks , TypeScript essentially erases undefined and null from the types. This means when this rule inspects the types from a variable, it will not be able to tell that the variable might be null or undefined , which essentially makes this rule useless.

You should be using strictNullChecks to ensure complete type-safety in your codebase.

If for some reason you cannot turn on strictNullChecks , but still want to use this rule - you can use this option to allow it - but know that the behavior of this rule is undefined with the compiler option turned off. We will not accept bug reports if you are using this option.

When Not To Use It ​

If your project is not accurately typed, such as if it's in the process of being converted to TypeScript or is susceptible to trade-offs in control flow analysis , it may be difficult to enable this rule for particularly non-type-safe areas of code. You might consider using ESLint disable comments for those specific situations instead of completely disabling this rule.

This rule has a known edge case of triggering on conditions that were modified within function calls (as side effects). It is due to limitations of TypeScript's type narrowing. See #9998 for details. We recommend using a type assertion in those cases.

Related To ​

• ESLint: no-constant-condition - no-unnecessary-condition is essentially a stronger version of no-constant-condition , but requires type information.
• strict-boolean-expressions - a more opinionated version of no-unnecessary-condition . strict-boolean-expressions enforces a specific code style, while no-unnecessary-condition is about correctness.

Resources ​

• Rule source
• Test source
• allowConstantLoopConditions
• allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing
• When Not To Use It

disallow ternary operators when simpler alternatives exist (no-unneeded-ternary)

The --fix option on the command line can automatically fix some of the problems reported by this rule.

It's a common mistake in JavaScript to use a conditional expression to select between two Boolean values instead of using ! to convert the test to a Boolean. Here are some examples:

Another common mistake is using a single variable as both the conditional test and the consequent. In such cases, the logical OR can be used to provide the same functionality. Here is an example:

Rule Details

This rule disallow ternary operators when simpler alternatives exist.

Examples of incorrect code for this rule:

Examples of correct code for this rule:

This rule has an object option:

• "defaultAssignment": true (default) allows the conditional expression as a default assignment pattern
• "defaultAssignment": false disallows the conditional expression as a default assignment pattern

defaultAssignment

When set to true , which it is by default, The defaultAssignment option allows expressions of the form x ? x : expr (where x is any identifier and expr is any expression).

Examples of additional incorrect code for this rule with the { "defaultAssignment": false } option:

Note that defaultAssignment: false still allows expressions of the form x ? expr : x (where the identifier is on the right hand side of the ternary).

When Not To Use It

You can turn this rule off if you are not concerned with unnecessary complexity in conditional expressions.

Related Rules

• no-nested-ternary

This rule was introduced in ESLint 0.21.0.

• Rule source
• Documentation source

© OpenJS Foundation and other contributors Licensed under the MIT License. https://eslint.org/docs/rules/no-unneeded-ternary

ESLint's no-unused-expressions Rule: Keeping Your Code Clean and Concise

Eslint's no-unused-expressions rule.

• ESLint is a popular tool that helps identify and fix potential issues in your JavaScript code.
• The no-unused-expressions rule specifically targets expressions whose result is not used in any meaningful way.
• This rule aims to improve code clarity and maintainability by removing unnecessary parts that don't affect the program's behavior.
• Unused expressions can clutter the code and make it harder to understand the intended logic.
• The rule is enabled by default in many ESLint configurations.
• You can adjust its severity (error or warning) or disable it entirely based on your project's requirements.

Sample Code:

• The rule allows certain expressions even if their result isn't explicitly assigned, such as function calls (due to potential side effects) and increment/decrement operators (which modify variables).
• Consider using this rule as a guide to write concise and readable code, but exercise judgment in cases where clarity might be improved by keeping an expression for specific purposes.
• When enabled as an error, the rule will cause your code to fail the linting process if it encounters unused expressions.
• You can fix these errors by either using the expression's result or removing the unnecessary part.

Disallow unused expressions

An unused expression which has no effect on the state of the program indicates a logic error.

For example, n + 1; is not a syntax error, but it might be a typing mistake where a programmer meant an assignment statement n += 1; instead. Sometimes, such unused expressions may be eliminated by some build tools in production environment, which possibly breaks application logic.

Rule Details

This rule aims to eliminate unused expressions which have no effect on the state of the program.

This rule does not apply to function calls or constructor calls with the new operator, because they could have side effects on the state of the program.

This rule does not apply to directives (which are in the form of literal string expressions such as "use strict"; at the beginning of a script, module, or function).

Sequence expressions (those using a comma, such as a = 1, b = 2 ) are always considered unused unless their return value is assigned or used in a condition evaluation, or a function call is made with the sequence expression value.

This rule, in its default state, does not require any arguments. If you would like to enable one or more of the following you may pass an object with the options set as follows:

• allowShortCircuit set to true will allow you to use short circuit evaluations in your expressions (Default: false ).
• allowTernary set to true will enable you to use ternary operators in your expressions similarly to short circuit evaluations (Default: false ).
• allowTaggedTemplates set to true will enable you to use tagged template literals in your expressions (Default: false ).
• enforceForJSX set to true will flag unused JSX element expressions (Default: false ).

These options allow unused expressions only if all of the code paths either directly change the state (for example, assignment statement) or could have side effects (for example, function call).

Examples of incorrect code for the default { "allowShortCircuit": false, "allowTernary": false } options:

Examples of correct code for the default { "allowShortCircuit": false, "allowTernary": false } options:

Note that one or more string expression statements (with or without semi-colons) will only be considered as unused if they are not in the beginning of a script, module, or function (alone and uninterrupted by other statements). Otherwise, they will be treated as part of a “directive prologue”, a section potentially usable by JavaScript engines. This includes “strict mode” directives.

Examples of correct code for this rule in regard to directives:

Examples of incorrect code for this rule in regard to directives:

allowShortCircuit

Examples of incorrect code for the { "allowShortCircuit": true } option:

Examples of correct code for the { "allowShortCircuit": true } option:

allowTernary

Examples of incorrect code for the { "allowTernary": true } option:

Examples of correct code for the { "allowTernary": true } option:

allowShortCircuit and allowTernary

Examples of correct code for the { "allowShortCircuit": true, "allowTernary": true } options:

allowTaggedTemplates

Examples of incorrect code for the { "allowTaggedTemplates": true } option:

Examples of correct code for the { "allowTaggedTemplates": true } option:

enforceForJSX

JSX is most-commonly used in the React ecosystem, where it is compiled to React.createElement expressions. Though free from side-effects, these calls are not automatically flagged by the no-unused-expression rule. If you’re using React, or any other side-effect-free JSX pragma, this option can be enabled to flag these expressions.

Examples of incorrect code for the { "enforceForJSX": true } option:

Examples of correct code for the { "enforceForJSX": true } option:

This rule was introduced in ESLint v0.1.0.

• Rule source
• Tests source

© OpenJS Foundation and other contributors Licensed under the MIT License. https://eslint.org/docs/latest/rules/no-unused-expressions

Boosting Readability and Consistency: Using Arrow Functions Effectively in JavaScript

OverviewRule: prefer-arrow-callbackLinter: ESLintPurpose: Encourages the use of arrow functions instead of traditional function expressions

• ESLint's object-curly-spacing Rule: Keeping Your JavaScript Objects Tidy
• Boost Code Readability: Leveraging ESLint's symbol-description Rule for Meaningful Symbol Values
• Understanding no-self-assign in ESLint: When to Avoid Assigning Variables to Themselves

Optimizing JavaScript for Clarity: The Power of ESLint's no-useless-computed-key Rule

Say Goodbye to Confusion: Using Constants to Replace Magic Numbers in Your Code

Eslint's no-dupe-else-if rule: preventing duplicate conditions for clearer code.

Unnecessary use of conditional expression for default assignment.eslintno-unneeded-ternary

openrisc-HW-tutorial-Xilinx.pdf

Openrisc-hw-tutorial-altera.pdf.

spring-framework-4.3.3.release-libs

优化下面代码.bg { width: 100%; height: 100vh; background-image: url('../../assets/img/info-bg.png'); background-size: 100% 100%; background-repeat: no-repeat; position: relative; font-family: AlibabaPuHuiTiR; .goBack { position: absolute; top: 34px; right: 65px; cursor: pointer; color: #ffffff; width: 181px; padding: 15px 10px; background: rgba(24, 31, 30, 0.52); border: 1px solid #4a524e; border-radius: 5px; font-size: 18px; font-family: AlibabaPuHuiTiR; z-index: 111; display: flex; flex-direction: row; justify-content: space-between; align-items: center; } .home-left { position: absolute; top: 18%; left: 40px; width: 41%; height: 76%; font-size: 24px; color: #ffffff; } .unit { font-size: 24px; color: #636363; } .home-left-title { font-size: 24px; color: #ffffff; line-height: 36px; } .home-right { position: absolute; top: 18%; right: 88px; width: 46%; height: 78%; } .model { display: flex; justify-content: center; align-items: center; height: 90%; } #threeContained { width: 100%; height: 100%; } .model-qk-img { width: 82%; height: 90%; background-image: url('../../assets/img/howo.png'); background-size: 100% 100%; background-repeat: no-repeat; } .model-zk-img { width: 56%; height: 90%; background-image: url('../../assets/img/heavyT.png'); background-size: 100% 100%; background-repeat: no-repeat; } .model-gj-img { width: 82%; height: 90%; background-image: url('../../assets/img/transit.png'); background-size: 100% 100%; background-repeat: no-repeat; } .car-online { margin-bottom: 50px; } } .day-data { display: flex; flex-direction: row; justify-content: space-between; align-items: center; height: 29%; margin-left: 30px; } .day-val { width: 40%; } .prefix { display: inline-block; width: 6px; height: 14px; background: #ffffff; margin-right: 20px; } .zh-title { margin-left: 30px; padding-top: 30px; font-size: 30px; font-weight: 700; text-align: left; color: #ffffff; line-height: 32px; letter-spacing: 0.3px; font-family: AlibabaPuHuiTiB; } .en-title { margin-left: 30px; font-size: 14px; font-weight: 400; text-align: left; color: #ffffff; line-height: 32px; letter-spacing: -0.91px; font-family: AlibabaPuHuiTiR; }

2023-06-06 18:10:33,041 info sqoop.sqoop: running sqoop version: 1.4.7 2023-06-06 18:10:33,075 warn tool.basesqooptool: setting your password on the command-line is insecure. consider using -p instead. 2023-06-06 18:10:33,218 info manager.mysqlmanager: preparing to use a mysql streaming resultset. 2023-06-06 18:10:33,218 info tool.codegentool: beginning code generation loading class com.mysql.jdbc.driver'. this is deprecated. the new driver class is com.mysql.cj.jdbc.driver'. the driver is automatically registered via the spi and manual loading of the driver class is generally unnecessary. 2023-06-06 18:10:33,782 info manager.sqlmanager: executing sql statement: select t.* from user_log as t limit 1 2023-06-06 18:10:33,825 info manager.sqlmanager: executing sql statement: select t.* from user_log as t limit 1 2023-06-06 18:10:33,834 info orm.compilationmanager: hadoop_mapred_home is /opt/module/hadoop-3.1.4 注: /tmp/sqoop-root/compile/5f4cfb16d119de74d33f1a0d776d5ae0/user_log.java使用或覆盖了已过时的 api。 注: 有关详细信息, 请使用 -xlint:deprecation 重新编译。 2023-06-06 18:10:35,111 info orm.compilationmanager: writing jar file: /tmp/sqoop-root/compile/5f4cfb16d119de74d33f1a0d776d5ae0/user_log.jar 2023-06-06 18:10:35,125 warn manager.mysqlmanager: it looks like you are importing from mysql. 2023-06-06 18:10:35,126 warn manager.mysqlmanager: this transfer can be faster use the --direct 2023-06-06 18:10:35,126 warn manager.mysqlmanager: option to exercise a mysql-specific fast path. 2023-06-06 18:10:35,126 info manager.mysqlmanager: setting zero datetime behavior to converttonull (mysql) 2023-06-06 18:10:35,130 error tool.importtool: import failed: no primary key could be found for table user_log. please specify one with --split-by or perform a sequential import with '-m 1'., 请参考网址https://www.car-vacation.com/e/action/listinfo/classid=16，写一个类似的html页面，要求给出完整的布局框架代码, vuecompilererror: unnecessary value binding used alongside v-model. it will interfere with v-model's behavior., bigdecimal.round_unnecessary, clang-tidy-checks, unresolved plugin: 'org.springframework.boot:spring-boot-maven-plugin:2.3.4.release', fatal error: call_and_retry_last allocation failed - javascript heap out of memory, waiting for the docker engine..., d:\git-global\toyo\src\main\webapp\app\entities\part\delete\part-delete-dialog.component.ts 26:11 error unnecessary conditional, value is always truthy @typescript-eslint/no-unnecessary-condition, runtimeerror: cuda out of memory. tried to allocate 256.00 mib, >conda clean --all, d:\microsoft vs code\demo10\src\store\module\menusmodule.js 178:8 error unnecessary semicolon no-extra-semi, 2023-06-09 09:46:11.022252: i tensorflow/core/common_runtime/gpu/gpu_device.cc:1900] ignoring visible gpu device (device: 0, name: geforce gt 610, pci bus id: 0000:01:00.0, compute capability: 2.1) with cuda compute capability 2.1. the minimum required cuda capability is 3.5. 2023-06-09 09:46:11.022646: i tensorflow/core/platform/cpu_feature_guard.cc:151] this tensorflow binary is optimized with oneapi deep neural network library (onednn) to use the following cpu instructions in performance-critical operations: avx avx2 to enable them in other operations, rebuild tensorflow with the appropriate compiler flags. warning:tensorflow:5 out of the last 9 calls to <function model.make_test_function.<locals>.test_function at 0x0000017bb39d0670> triggered tf.function retracing. tracing is expensive and the excessive number of tracings could be due to (1) creating @tf.function repeatedly in a loop, (2) passing tensors with different shapes, (3) passing python objects instead of tensors. for (1), please define your @tf.function outside of the loop. for (2), @tf.function has experimental_relax_shapes=true option that relaxes argument shapes that can avoid unnecessary retracing. for (3), please refer to https://www.tensorflow.org/guide/function#controlling_retracing and https://www.tensorflow.org/api_docs/python/tf/function for more details. warning:tensorflow:6 out of the last 11 calls to <function model.make_test_function.<locals>.test_function at 0x0000017bb3ae83a0> triggered tf.function retracing. tracing is expensive and the excessive number of tracings could be due to (1) creating @tf.function repeatedly in a loop, (2) passing tensors with different shapes, (3) passing python objects instead of tensors. for (1), please define your @tf.function outside of the loop. for (2), @tf.function has experimental_relax_shapes=true option that relaxes argument shapes that can avoid unnecessary retracing. for (3), please refer to https://www.tensorflow.org/guide/function#controlling_retracing and https://www.tensorflow.org/api_docs/python/tf/function for more details., out of memory. gc overhead limit exceeded, k-means算法的elkan.

【源码编号 : MF00011】Java进销存ERP管理系统源码

监视和测量仪器清单目录表.docx

ChatGPT的工作原理-2023最新版

嵌入式系统设计：单片机与外设模块的接口设计与优化

halcon控件中点击区域选中已存在区域

毕业论文jsp714学生管理系统 带论坛ssh.doc

"互动学习：行动中的多样性与论文攻读经历", 电源管理在单片机系统设计中的考虑因素, java写一个存储，前端每上传一个文件，将文件路径写入存储.

Rules in ESLint are grouped by category to help you understand their purpose.

No rules are enabled by default. The "extends": "eslint:recommended" property in a configuration file enables rules that report common problems, which have a check mark below.

The --fix option on the command line automatically fixes problems (currently mostly whitespace) reported by rules which have a wrench below.

Possible Errors

These rules relate to possible syntax or logic errors in JavaScript code:

Best Practices

These rules relate to better ways of doing things to help you avoid problems:

Strict Mode

These rules relate to strict mode directives:

These rules relate to variable declarations:

Node.js and CommonJS

These rules relate to code running in Node.js, or in browsers with CommonJS:

Stylistic Issues

These rules relate to style guidelines, and are therefore quite subjective:

ECMAScript 6

These rules relate to ES6, also known as ES2015:

These rules have been deprecated in accordance with the deprecation policy , and replaced by newer rules:

These rules from older versions of ESLint (before the deprecation policy existed) have been replaced by newer rules:

Search code, repositories, users, issues, pull requests...

Provide feedback.

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly.

To see all available qualifiers, see our documentation .

• Notifications

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

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

'no-unneeded-ternary' does not catch ternary issues with data properties #11852

BrandonYeager commented Jun 17, 2019

platinumazure commented Jun 17, 2019

Sorry, something went wrong.

eslint-deprecated bot commented Jul 21, 2019

No branches or pull requests

disallow assignment operators in conditional statements (no-cond-assign)

The "extends": "eslint:recommended" property in a configuration file enables this rule.

In conditional statements, it is very easy to mistype a comparison operator (such as == ) as an assignment operator (such as = ). For example:

There are valid reasons to use assignment operators in conditional statements. However, it can be difficult to tell whether a specific assignment was intentional.

Rule Details

This rule disallows ambiguous assignment operators in test conditions of if , for , while , and do...while statements.

This rule has a string option:

• "except-parens" (default) allows assignments in test conditions only if they are enclosed in parentheses (for example, to allow reassigning a variable in the test of a while or do...while loop)
• "always" disallows all assignments in test conditions

except-parens

Examples of incorrect code for this rule with the default "except-parens" option:

Examples of correct code for this rule with the default "except-parens" option:

Examples of incorrect code for this rule with the "always" option:

Examples of correct code for this rule with the "always" option:

Related Rules

• no-extra-parens

This rule was introduced in ESLint 0.0.9.

• Rule source
• Documentation source