Control Flow: Conditionals & Loops

Easy

In plain terms

Control flow is the order in which statements run. Conditionals let you branch: "if this is true, do A; else do B." Loops let you repeat: "do this while a condition holds" or "for each item, do this."

Mastering conditionals and loops is essential. They appear in every program. Nested conditionals and loops can get complex—keeping them shallow and readable is a skill. Many bugs come from off-by-one errors in loops or missing branches in conditionals.

What you need to know

•if/else, switch for branching
•for, while for repetition
•Conditions must be clear and complete

Example

Code is language-agnostic in spirit; adapt the idea to your language:

// Conditionals
if (score >= 60) {
  console.log("Pass");
} else {
  console.log("Fail");
}

// Loop
for (let i = 0; i < 3; i++) {
  console.log("Step", i + 1);
}

Why this matters

Control flow is behind every coding question: loops to traverse data, conditionals for business rules. Off-by-one and missing edge cases are common interview pitfalls.

How it connects

Control flow appears inside functions and methods. In OOP, class methods use the same conditionals and loops; SOLID and clean code advise keeping that logic simple and readable.

Interview focus

Be ready to explain these; they come up often.

▸When to use for vs while; when to use switch vs if/else chain.
▸Edge cases: empty input, single element, boundary values.
▸Avoid deep nesting: early returns and guard clauses keep code flat.

Learn more

Dive deeper with these resources:

W3Schools