Declaration or statement expected error in TypeScript
This article explains Declaration or statement expectedthe error in JavaScript or TypeScript and why the compiler throws this error. All the major causes of this error will be discussed, and how to avoid it in the developer community.
预期的声明或语句Errors
in JavaScript or TypeScript
Errors in JavaScript or TypeScript occur when we have syntax errors in our code Declaration or statement expected.
For example, consider using incorrect syntax to destructure an object in a file, exporting a module in a file with the wrong name, or missing or inconsistent parentheses.
Consider the following code example where different appears due to a syntax error in the code Declaration or statement expected.
let oneData: number;
const obj = {
val: 1,
};
// 1. ⛔️ Parsing error: Declaration or statement expected.
{ oneData } = obj; // 👈️ this must be wrapped in parenthesis
const sumObj = (a: number, b: number) => a + b;
// 2. ⛔️ Error: Parsing error: Declaration or statement expected.eslint
export sumObj // 👈️ should be export {sum}
// 3. Make sure you're not using reserved words
const caseVal = 'hello world' // 👈️ case is reserved word
The above code produces the following error, written below.
//output or errors
Variable 'one' is used before being assigned.
Declaration or statement expected. This '=' follows a block of statements, so if you intend to write a destructuring assignment, you might need to wrap the whole assignment in parentheses.
Declaration or statement expected.
'case' is not allowed as a variable declaration name.
Variable declaration expected.
Variable declaration expected.
Consider the following code, which compiles correctly without Declaration or statement expectederrors.
let val: number;
const obj = {
val: 1,
};
// ✅ OK
({ val } = obj); // 👈️ this must be wrapped in parenthesis
console.log(val); // 👉️ 1
The above code produces the following output.
1
Errors can also sometimes occur when you export something that has been previously declared 预期声明或声明. Whenever you need to do this, enclose the export in curly braces.
const objSum = (a: number, b: number) => a + b;
// ✅ OK
export { objSum };
For reprinting, please send an email to 1244347461@qq.com for approval. After obtaining the author's consent, kindly include the source as a link.
Related Articles
Handling exceptions with try..catch..finally in TypeScript
Publish Date：2025/04/15 Views：170 Category：TypeScript
-
This article will discuss try..catch..finally handling exceptions in TypeScript using the statement. Handling exceptions in TypeScript In TypeScript, try..catch..finally a block handles exceptions that occur during program runtime. It allow
Convert JSON object to a class in TypeScript
Publish Date：2025/04/15 Views：80 Category：TypeScript
-
Data on the internet flows in the form of strings, which can be converted into a very popular format called JSON. The JSON representation of this data usually represents an object or even a class in TypeScript. TypeScript provides the abili
Update TypeScript to the latest version using NPM
Publish Date：2025/04/15 Views：119 Category：TypeScript
-
This article provides a guide to update to the latest version of TypeScript using npm, which is the best and most popular method used by developers. This also gives us an in-depth look at what npm is and why to use it. Node Package Manager
Using jQuery and TypeScript
Publish Date：2025/04/15 Views：148 Category：TypeScript
-
This article provides the basic understanding and concepts of using jQuery with TypeScript. It guides on how to use jQuery in TypeScript through a coding example and outputs using various methods in TypeScript and provides knowledge about w
Checking for undefined in TypeScript
Publish Date：2025/04/15 Views：196 Category：TypeScript
-
This article will demonstrate how programmers can check for undefined in TypeScript using various coding examples and situations. It not only gives you an understanding of checking for undefined in TypeScript, but also helps in differentiat
exclude attribute in TypeScript
Publish Date：2025/04/15 Views：190 Category：TypeScript
-
This article will discuss excluding properties from a TypeScript type. The exclude property is used to create another type from an existing type with fewer or modified properties. Omit Exclude properties from types in TypeScript TypeScript
Function return types in TypeScript
Publish Date：2025/04/15 Views：174 Category：TypeScript
-
TypeScript is a strongly typed language and it is always encouraged to define the types correctly for all variables used in TypeScript. These types can help in development later, especially during debugging. In addition to variables, functi
Dictionary or map type in TypeScript
Publish Date：2025/04/15 Views：131 Category：TypeScript
-
Dictionaries or maps are used to quickly retrieve items from an object. TypeScript does not have any concept of maps or dictionaries. Plain JavaScript has objects that can set and retrieve key-value pairs. TypeScript provides Record types t
Regular expressions in TypeScript
Publish Date：2025/04/15 Views：104 Category：TypeScript
-
RegExp Is a regular expression used to match a fixed set of characters in a target string using TypeScript. RegExp Objects have many properties and methods. Each property has different options when pattern matching. Using regular expression
