property assignment expected ts(1136) react native

Fix – Property assignment expected. ts(1136)

The error “error TS1136: Property assignment expected.” In typescript and Javascript occurs for various reason. In this ts tutorial, we will see why the error occurs and how to solve it in VSCODE. The error mainly occurs when you have an already existing babel project and you try to transition it to Typescript . The compiler will throw an error in reference to object destructuring codes like var user = {...this.props.userName}; and you might think the syntax of object destructuring in JS is different from typescript if the code previously work in babel. But the syntax is the same just that with TS you have to use an interface to define your state.

We have defined a state using an interface which represent the structure of how our user object is going to be like. Then we did the destructuring by assigning a value to the ‘userName’ property which already exist. And in the last line of the above code, we appended a new property to the state, but bear in mind is not part of the properties defined in the interface. So why then did we not get an error that says ‘userAge’ is not a known property of State? Well note that we did used …user to append the ‘userAge’ to whatever properties already exist in the user variable (we weren’t appending a new property to the state itself).

With the interface already defined, we can move ahead and check the properties and emit some values.

Check also, Property does not exist on type ‘{}’ in TypeScript

Also, if you try to create a simple hello world application and inside the render() method you surround the return statement with a curry-braces instead of parenthesis, you will encounter the above error. Look at below code example and how it can be solved.

There is a bug in the above code and if we run the application this is what is presented on the console.

error message: at <div , I got “Property assignment expected.ts(1136)” at className, I got 2 errors Unreachable code detected.ts(7027) ‘;’ expected.ts(1005)

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Property assignment expected. ts(1136)

I am following book Learning React, chapter 13 page 158, to first create-react-app helloworld and create HelloWorld.js

error message: at <div , I got “Property assignment expected.ts(1136)” at className, I got 2 errors Unreachable code detected.ts(7027) ‘;’ expected.ts(1005)

package.json { “name”: “helloworld”, “version”: “0.1.0”, “private”: true, “dependencies”: { “ @testing-library /jest-dom”: “^4.2.4”, “ @testing-library /react”: “^9.5.0”, “ @testing-library /user-event”: “^7.2.1”, “react”: “^16.14.0”, “react-dom”: “^16.14.0”, “react-scripts”: “3.4.3” }, “scripts”: { “start”: “react-scripts start”, “build”: “react-scripts build”, “test”: “react-scripts test”, “eject”: “react-scripts eject” }, “eslintConfig”: { “extends”: “react-app” }, “browserslist”: { “production”: [ “>0.2%”, “not dead”, “not op_mini all” ], “development”: [ “last 1 chrome version”, “last 1 firefox version”, “last 1 safari version” ] } }

I am using visual studio code Version: 1.50.0 Commit: 93c2f0fbf16c5a4b10e4d5f89737d9c2c25488a3 Date: 2020-10-07T06:01:33.073Z Electron: 9.2.1 Chrome: 83.0.4103.122 Node.js: 12.14.1 V8: 8.3.110.13-electron.0 OS: Linux x64 5.4.0-51-generic

Can you help? Thanks!

Hi. Your jsx (html) should be wrapped by parens ( () ) or nothing at all, not curly braces ( {} ). I think that’s what is causing the error.

Thanks a lot. That is it.

Home » Introduction and Basics » Typescript object destructuring results in property assignment expected

Typescript object destructuring results in property assignment expected

Introduction.

Typescript is a popular programming language that adds static typing to JavaScript. It provides developers with the ability to catch errors during development and improve code quality. However, like any programming language, Typescript has its own set of challenges and issues that developers may encounter. One common issue is the “Typescript object destructuring results in property assignment expected” error. In this article, we will explore this error and provide solutions with examples.

The “Typescript object destructuring results in property assignment expected” error occurs when you try to destructure an object but forget to provide a default value for the property being destructured. Let’s take a look at an example:

In this example, we are trying to destructure the “person” object and assign the value of the “name” property to a variable called “name”. However, since we did not provide a default value for the “name” property, Typescript throws the “Typescript object destructuring results in property assignment expected” error.

To solve this error, we need to provide a default value for the property being destructured. We can do this by using the assignment operator (=) and specifying a default value after the property name. Let’s modify our previous example to include a default value:

In this modified example, we have provided a default value of an empty string (“”) for the “name” property. Now, even if the “name” property is not present in the “person” object, the destructuring assignment will not throw an error.

The “Typescript object destructuring results in property assignment expected” error can be easily solved by providing a default value for the property being destructured. By doing so, we ensure that the destructuring assignment does not throw an error even if the property is not present in the object. This helps in writing more robust and error-free Typescript code.

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Unexpected token. A constructor, method Error in TS [Fixed]

Last updated: Feb 27, 2024 Reading time · 3 min

# Unexpected token. A constructor, method Error in TS

The "Unexpected token. A constructor, method, accessor, or property was expected" error occurs when we use the var or let keywords to declare a class property or the function keyword in a class.

To solve the error, remove the var , let and function keywords from your class.

Here are 2 examples of how the error occurs.

We used the var and let keywords to assign properties to the class and the function keyword to declare class method.

To resolve the issue, remove the var , let and function keywords from your class.

The class has 2 propertied - a and b and a method named myFunction .

# Taking arguments via the constructor method

You will often have to take arguments when creating class instances. You can do that via the constructor method.

Notice that we assigned the a and b properties inside the constructor method and we aren't using the var , let or function keywords anywhere inside the class.

The class in the example is a more concise version of the following class.

We had to type the a and b class properties twice to achieve the same result.

# Using default values for constructor parameters

You can also use default values for constructor parameters.

We created an instance of the class without passing any parameters to the constructor function, so the a and b properties are set to the default values.

# Using arrow functions for class methods

You can also use arrow functions for class methods.

Notice that we aren't using the const , let or var keywords in the method's definition.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Get Argument types for Function/Constructor in TypeScript
• Property has no initializer and is not definitely assigned in the constructor
• Class constructor cannot be invoked without 'new' in JS/TS

Borislav Hadzhiev

Web Developer

Copyright © 2024 Borislav Hadzhiev

React Native 0.71: TypeScript by Default, Flexbox Gap, and more...

Today we’re releasing React Native version 0.71! This is a feature-packed release including:

• TypeScript by default
• Simplifying layouts with Flexbox Gap
• Web-inspired props for accessibility, styles, and events
• Restoring PropTypes
• Developer Experience Improvements
• New Architecture Updates

In this post we’ll cover some of the highlights of 0.71.

For a full list of changes, check out CHANGELOG.md .

TypeScript by default ​

In this release, we’re investing in the TypeScript experience of React Native.

Starting with 0.71, when you create a new React Native app via the React Native CLI you'll get a TypeScript app by default. The new project is already set up with a tsconfig.json so out of the box your IDE will help you write typed code right away.

We’re also offering built-in, more accurate TypeScript declarations directly from the react-native package. This means you won’t need @types/react-native any longer, and the types will be updated in lockstep with React Native releases.

Finally, our documentation has been updated to feature TypeScript for all examples.

After upgrading to React Native 0.71, we recommend removing @types/react-native from your package.json devDependencies .

For more details on this change, including migration steps and how this affects Flow users, check out our previous post First-class Support for TypeScript .

Simplifying layouts with Flexbox gap ​

With React Native you can flexibly layout components on different screen sizes using Flexbox. Browsers have supported the Flexbox properties gap , rowGap , and columnGap , which allow you to specify the amount of space between all items in a Flexbox.

These properties have been long requested in React Native, and 0.71 adds initial support for gaps defined using pixel values. In future versions, we will add support for more values, such as percentages.

To see why this is useful, imagine trying to build a responsive layout with variably sized cards, 10px apart from each other, hugging the edges of the parent container. Trying to accomplish this layout with child margins can be tricky.

The following shows a layout where we start by giving each child margin: 10 style:

Margins are applied uniformly to the edges of all children and don’t collapse under Flexbox, giving us spacing at the exterior of the cards, and double the space on the interior compared to what we wanted. We can get around this by applying non-uniform margins, using negative margins on the parent, halving our intended spacing, etc, but it can be made much easier.

With flex gap, this layout can be achieved by setting gap: 10 on the container for a 10 pixel gap between the interior of the cards:

For more information on Flexbox gaps, see this blogpost from CSS Tricks .

Web-inspired props for accessibility, styles, and events ​

This release includes a number of new props inspired by web standards to align React Native’s APIs across many platforms. These new props are purely additive so there are no expected migrations or change of behavior for equivalent accessibility, behavior, or style props.

For any new prop alias introduced, if there is an existing prop with a different name and both are specified, the new alias prop value will take precedence. For example, this release adds a src prop alias for source on the Image component to align with the src prop on web. If both src and source are provided, the new src prop will be used.

For more background on aligning React Native to web standards, check out this proposal and related discussion .

Accessibility ​

We introduced ARIA props as alias to existing React Native accessibility props.

These props now exist on all core components of React Native: aria-label , aria-labelledby , aria-modal , id , aria-busy , aria-checked , aria-disabled , aria-expanded , aria-selected , aria-valuemax , aria-valuemin , aria-valuenow , and aria-valuetext .

We also introduced equivalent web behavior for: aria-hidden , aria-live , role , and tabIndex .

See this issue for more details.

Component-Specific Behavior ​

There were also props introduced to align prop names with equivalent DOM prop names for core components.

• Image : alt , tintColor , crossOrigin , height , referrerPolicy , src , srcSet , and width .
• TextInput : autoComplete , enterKeyHint , inputMode , readOnly , and rows .

To align with certain CSS styles, there have been feature extensions for the following styles:

• aspectRatio now supports string values
• fontVariant now supports space-separated string values
• fontWeight now supports number values
• transform now supports string values

The following aliases have been added to shadow existing React Native styles:

• pointerEvents
• verticalAlign

Finally, we also added an opt-in implementation of PointerEvents

Once enabled, the following handlers on View will support hover:

• onPointerOver , onPointerOut
• onPointerEnter , onPointerLeave

These events are also implemented in Pressability for new opt-in support for hover.

To enable these features, set the following flags to true:

You’ll also need to enable React feature flags on your Android and iOS native setup.

Check out our dedicated PointerEvents post to learn more.

Restoring PropTypes ​

React Native’s prop types, such as ViewPropTypes and Text.propTypes , were deprecated in 0.66 and accessing them would output deprecation warnings. When they were removed in 0.68, many developers began experiencing errors when upgrading to the latest version of React Native.

After some investigation, we realized that a couple issues prevented the community from taking action on the deprecation warnings. First, the deprecation warning was not always actionable which caused people to ignore them ( issue one , issue two ). Second, the deprecation warnings were being incorrectly filtered by LogBox.ignoreLogs . Both of these have now been fixed, but we want to give people more time to upgrade the deprecated call sites.

So in this release we are adding back React Native’s propTypes so that it is easier for people to upgrade and migrate their code to avoid using them. The deprecated-react-native-prop-types package has also been updated for all of the props in 0.71. In the future, we plan to proceed with the deprecation and remove prop types once again. We expect that when we revisit the removal, the community will experience significantly fewer issues.

As part of this change, we are also removing the console filtering from LogBox.ignoreLog . This means logs that you have previously filtered with Logbox.ignoreLog will start appearing again in the console when you upgrade.

This is expected, because it allows logs such as deprecation warnings to be found and fixed.

Developer Experience Improvements ​

React devtools ​.

In this release, we've brought two popular React DevTools features on web to React Native.

"Click to inspect" is the option in the top left corner of React Dev Tools that allows you to click on an item in the app to inspect it in Dev Tools, similar to the Chrome element inspector.

Component highlighting will highlight the element you select in DevTools in the app so you can see which React components line up with which on-screen elements.

Here are both features in action:

In React Native 0.70, we made Hermes the default engine for React Native .

In React Native 0.71, we’re upgrading Hermes with a few notable improvements:

• Improve source maps : By loading source maps over the network with Metro we’ve restored the ability to use source maps in recent versions of Chrome Dev Tools outside of Flipper.
• Improve JSON.parse performance : This version includes a performance optimization that improves the performance of JSON.parse up to 30%.
• Add support for .at() : Hermes now supports .at() for String , TypedArray , and Array .

For a full list of changes see the Road to 71 issue .

New Architecture ​

This release brings many improvements to the experimental New Architecture experience based on user feedback and reports we collected so far.

• Reduced build times : The new distribution model uses Maven Central, which allows us to greatly reduce the build time on Android, resolves many build problems on Windows, and provides a more seamless experience with the New Architecture. Read more here .
• Write less C++ code : You can now enable the New Architecture without having to add any C++ code in your app and the CLI app template has been cleaned of all the C++ code and the CMake files. Read more here .
• Better encapsulation of iOS app setup : On iOS, we followed a similar approach to Android and encapsulated most of the logic to set up the New Architecture in the RCTAppDelegate class, which will simplify upgrades in the future with fewer manual breaking changes.
• Better dependency management on iOS : For library maintainers, we've added a new install_module_dependencies function to call inside your package podspec which will install all the required dependencies for the New Architecture.
• Bug fixes and better IDE support : we fixed several bugs and issues (like better IDE support for Android ) that were reported by our users in the New Architecture Working Group .

As a reminder, the New Architecture is still an experimental API experience as we iterate on changes to make adoption easier. Please try out the new simplified steps in the New Architecture documentation and post any feedback you have to the New Architecture Working Group .

Other Notable Fixes ​

• Better stack frame collapsing : We've updated the list of internal frames for React Native so LogBox will show your code more often rather than internal React Native frames, helping you to debug issues faster.
• Build time improvements: We migrated assets to Maven Central for prefabs to improve build times (both iOS and Android) for Hermes in both the current and new architectures.
• Android template improvements : The Android template was heavily cleaned and now fully relies on the React Native Gradle Plugin. You can find the configuration instructions directly inside the template or in the new dedicated page on the website .

Breaking changes ​

• Changes to Console Logging: LogBox.ignoreLog no longer filters console logs. This means you will start seeing logs in the console that you have silenced in LogBox. See this comment for more details.
• Removed AsyncStorage and MaskedViewIOS : These components have been deprecated since version 0.59 , so it’s time we remove them entirely. For alternatives, please check React Native Directory for community packages that cover those use cases.
• JSCRuntime moved to react-jsc: react-jsi is now split into react-jsc and react-jsi. If you use JSCRuntime, you will need to add react-jsc as a dependency ( facebook/react-native@6b129d8 ).

Acknowledgements ​

This release is possible thanks to the work of 70+ contributors adding over 1000 commits.

We especially want to thank those who contributed to these major React Native projects:

• Flexbox Gap Support : @intergalacticspacehighway and @jacobp100 .
• Web-inspired props : @gabrieldonadel @dakshbhardwaj @dhruvtailor7 @ankit-tailor @madhav23bansal .
• Codegen Improvements : @AntoineDoubovetzky , @MaeIg , @Marcoo09 , @Naturalclar , @Pranav-yadav , @ZihanChen-MSFT , @dakshbhardwaj , @dhruvtailor7 , @gabrieldonadel , @harshsiri110 , @ken0nek , @kylemacabasco , @matiassalles99 , @mdaj06 , @mohitcharkha , @tarunrajput , @vinayharwani13 , @youedd , @byCedric .

Finally, thanks to @cortinico , @kelset , @dmytrorykun , @cipolleschi , and @titozzz for cutting this release!

Try out 0.71.0 now! ​

For React Native CLI users, see the upgrade documentation for how to update your existing project, or create a new project with npx react-native init MyProject .

React Native version 0.71 will be supported in Expo SDK version 48.

0.71 is now the latest stable version of React Native and 0.68.x versions are now unsupported. For more information see React Native’s support policy .

• Simplifying layouts with Flexbox gap
• React DevTools
• New Architecture
• Other Notable Fixes
• Breaking changes
• Acknowledgements
• Try out 0.71.0 now!

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Property 'push' does not exist on type CompositeNavigationProp #11024

kjossendal commented Nov 21, 2022 • edited

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TypeScript is a language for application-scale JavaScript development. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.

Typescript errors on code that works using React Native Libraries. Specifically React Navigation and React Native Paper

So I am using TypeScript for the first time, and I really like that it prevents me from making really stupid errors that I used to make all the time. But the main way I know to get it to not yell at me is to declare an interface above the default function that is going to be passed through, make the props of type of the declared interface, and there we go. This is really straight forward for custom things you make yourself, but I am confused on how to do things for components imported from libraries. The first error I get is some version of these two errors in conjunction:

And then there is also some version of these two errors in conjunction:

The code works as I have it but because of the type system I guess it's warning me that it may not in all circumstances? So any help would be appreciated so I don't keep going and build up dozens of error messages

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Expected an assignment or function call and instead saw an expression

Reactjs guru.

• February 10, 2024

The error message “ Expected an assignment or function call and instead saw an expression ” in React.js typically arises due to a missing return statement within a function, where a value is expected to be returned but isn’t.

Table of Contents

Understanding the Error:

The error message “Expected an Assignment or Function Call and Instead Saw an Expression” typically occurs in React.js when a function or callback does not return a value as expected. This can happen when we use methods like map() without properly returning a value from the callback function.

Causes of the Error:

Forgetting to use a return statement in a function or callback can lead to this error. This often occurs when we use array methods map() where a return value is expected from the callback function.

Solving the Error:

There are two main approaches to solving the “Expected an Assignment or Function Call and Instead Saw an Expression” error in React.js: using explicit and implicit returns.

1. Using Explicit Return:

Explicitly using a return statement ensures that functions or callbacks return the expected values. This is especially important when we use array methods like map() .

2. Using Implicit Return:

Using an implicit return with arrow functions provides a concise and elegant solution. This shorthand syntax is suitable for simple functional components and ensures that functions implicitly return values without using the return keyword.

Conclusion:

 The “Expected an Assignment or Function Call and Instead Saw an Expression” error in React.js occurs when functions or callbacks fail to return values as expected, commonly due to incomplete definitions or incorrect usage of array methods. To fix this error, we can use explicit returns and implicit returns.

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• Can Not Read Properties of Undefined Reading Map in React JS
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使用装饰器可能会提示 Property assignment expected.Vetur(1136)

因为使用eslint进行代码格式检查，所以可以关闭vetur验证script的能力，请在vscode settings里面添加下面代码

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问 为什么语法错误“属性赋值expected.ts(1136)”发生时使用回勾键？ EN

当我运行这个脚本时，会发生 TS1136: Property assignment expected. 错误。你怎么能解决这个问题？

这是sample.ts。

当然，这段代码很好用。

Stack Overflow用户

发布于 2022-09-16 06:28:40

您需要在 [] 中包装动态键以使它们工作。

https://stackoverflow.com/questions/73740720

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React Typescript - ',' expected.ts(1005)

I'm using Typescript in an React app with Graphql .

I'm getting an error:

',' expected.ts(1005)

The only answers I find say that typescript is out of date but I'm using 3.7.2

The error occurs here at line data.recipe.map(recipe =>

package.json :

You can't put statements in JSX curly braces, only expressions. You can replace the if statement with an inline && expression.

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