What Is the “declare” Keyword?

  • The “declare” keyword informs the TypeScript compiler that a variable or method exists in another file (typically a JavaScript file).
  • It’s similar to an “import” statement but doesn’t import anything; instead, it provides type information.

Explain when to use “declare” keyword in TypeScript

In TypeScript, the “declare” keyword is important in ambient declarations. These declarations allow us to integrate third-party JavaScript libraries seamlessly into our TypeScript codebase. Think of it as a bridge that connects TypeScript with existing JavaScript code. In this article, we’ll explore when and how to use the “declare” keyword effectively in TypeScript.

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What Is the “declare” Keyword?

The “declare” keyword informs the TypeScript compiler that a variable or method exists in another file (typically a JavaScript file).It’s similar to an “import” statement but doesn’t import anything; instead, it provides type information....

Use Cases for “declare” Keyword

Third-Party Libraries: When working with JavaScript libraries like jQuery, Node.js, or other external dependencies, we can use “declare” to access their methods and variables.Legacy JavaScript Code: Suppose you have an existing JavaScript file with valuable variables or functions. By declaring them in TypeScript, you can leverage their functionality without rewriting everything....