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Conditionals & Loops in JSX

Discover how to integrate control flow logic directly into your JSX to dynamically render interfaces.

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Tutor:React allows us to write UI logic directly inside our JSX! However, we can't use traditional statement loops (like `for`) or conditionals (like `if`) inline. Let's see the right way.


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Concept: Conditionals

JSX requires expressions. Use the ternary operator ? : or the logical AND && to render conditionally.

System Check

Can you use standard 'if(condition){}' inside JSX brackets?

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Logic in Your Interface:
Conditionals & Loops

Author

Pascual Vila

Frontend Instructor // Code Syllabus

In React, JSX allows you to incorporate JavaScript logic to create dynamic interfaces. Two fundamental concepts in this process are conditionals and loops.

Conditional Rendering

Conditional rendering allows you to show or hide elements based on certain conditions. In JSX, this is achieved using expressions.

  • Ternary Operator (`? :`): Evaluates a condition and returns one of two outcomes. Perfect for if/else logic inside JSX.
  • Logical AND (`&&`): Renders an element only if the condition is true. If false, React ignores it and renders nothing.

Using Loops in JSX

To iterate over lists and dynamically render elements, you use array methods like map().

Important Rule: It is important to remember that standard `if` statements and `for` loops are statements, not expressions, in JavaScript. Therefore, they cannot be used directly inline within JSX curly braces. Always use expressions like map or ternaries.

View Transcript Notes+

Discover how to integrate control flow logic directly into your JSX using conditionals (if-else, ternary operators) and loops (map). Learn to dynamically render different elements or lists of elements based on your application's state. Understand best practices, such as requiring unique key props in `.map()`, to keep your UI adaptable.

JSX Logic Glossary

Ternary Operator

An inline if-else statement used to conditionally render one element or another.

snippet.jsx

Logical &&

Short-circuit evaluation. If the left side is true, the right side renders.

snippet.jsx

Array Map()

Iterates through an array to render a list of React elements.

snippet.jsx

Key Prop

A special string attribute you need to include when creating lists of elements so React can track them.

snippet.jsx