Conditionals
Conditionals allow your code to take different paths depending on whether an expression evaluates to true or false.
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📋 Copy JavaScript Conditionals & Switch Template
const status = "success";
// Switch Statement with Block Scoping
switch (status) {
case "loading": {
const spinner = true;
break;
}
case "success": {
const data = fetchCached();
break;
}
default:
throw new Error(`Unhandled status: ${status}`);
}
// Optional Chaining with Nullish Coalescing
const street = user?.address?.street ?? "Unknown Street";⚠️ 5 Fatal Traps & JavaScript Pitfalls
Trap #1: Switch Statement Fallthrough Bug
Omitting a
break statement causes execution to fall through into subsequent case statements regardless of whether their condition matched.Trap #2: Lexical Scope Clashes Inside Switch Cases
Variables declared with
let or const inside a switch statement share a single block scope unless wrapped in curly braces case "x": { const a = 1; break; }.Trap #3: Optional Chaining on Non-Function Properties
Calling
obj?.method() prevents errors if obj is null/undefined, but if method exists and is NOT a function, it still throws a TypeError: obj.method is not a function.Trap #4: Unintended Assignment in If Statement
Typing
if (status = "admin") assigns the string instead of comparing it, mutating the variable and always evaluating to truthy.Trap #5: Deep Nested Ternary Readability Nightmare
Chaining multiple ternaries (
a ? b : c ? d : e ? f : g) obscures business logic. Flatten code using early returns or object strategy dictionaries.💬 Frequently Asked Questions
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