Basics
TS Variables
Declaring TypeScript Variables
TypeScript variables use let and const with type annotations.
Introduction to TypeScript Variables
TypeScript is a statically typed superset of JavaScript that adds optional type annotations. One of the core features of TypeScript is its ability to define variables using let and const with type annotations, providing better type safety and code clarity.
Using let and const
In TypeScript, let and const are used to declare variables. The let keyword allows you to declare variables whose value can change over time, whereas const is used for variables whose value should remain constant.
Using let:
Using const:
Type Annotations
TypeScript allows you to add type annotations to variables to specify what type of data a variable can hold. This helps catch errors at compile time rather than at runtime. Type annotations are added by using a colon followed by the type name.
Type Inference
TypeScript can automatically infer the type of a variable based on its initial value. This means that you do not always need to explicitly declare the type of a variable. Type inference helps reduce verbosity while still maintaining type safety.
Best Practices for Using Variables in TypeScript
- Always prefer
constoverletwhen the variable's value should not change. - Use type annotations for complex types or when it improves code readability.
- Leverage type inference for simple cases to keep the code concise.
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