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TypeScript

TS103

3

Types Are Guard Rails

Types tell TypeScript what kind of value is expected.

What is a type in TypeScript?

A type is a rule that describes what kind of value a variable, function input, function output, or object property should have.

TypeScript types are guard rails.

They do not drive the car for you.

They help stop obvious mistakes before the program runs.

Common basic types include string, number, and boolean.

Once the expected type is clear, bad values are easier to catch.

Basic TypeScript types

string means text.

number means a numeric value.

boolean means true or false.

Each variable now has an expected kind of value.

TypeScript warns when the value does not match the expected type.

Clarity

Types make expected data easier to understand.

Checking

TypeScript can catch wrong assignments.

Editors

Editors can offer better help when types are known.

Maintenance

Future changes are safer when data expectations are clear.

Unclear data

Clear boolean

Ask ChatGPT: "Identify the type of each variable and explain what wrong values TypeScript should reject."

Create a string variable.

Create a number variable.

Create a boolean variable.

Try assigning the wrong type.

Explain why types are guard rails.

Thinking a type is the same as the value.

Using string values for true or false.

Removing types to avoid fixing mistakes.

Forgetting that number covers integers and decimals.

Ignoring editor warnings.

Use basic TypeScript types as guard rails for variables.