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Use if...else for ranges, compound conditions, or different predicates; use switch when one value is matched against several discrete alternatives. Choose based on what the logic means, not a fixed number of branches. A switch uses strict equality and can continue into later cases if you omit break.
When is if...else the better fit?
Use if...else when branches test conditions rather than compare one expression against a list of exact values. It directly expresses ordered checks, ranges, and compound logic involving operators such as && and ||. The order matters if conditions overlap: JavaScript runs the first branch whose condition is true.
if (temperature < 0) {
label = "freezing";
} else if (temperature < 20) {
label = "cool";
} else {
label = "warm";
}These conditions describe ranges, so exact-value cases would not express the logic as naturally. MDN notes that if...else is useful when choices involve complex conditions or substantial code. MDN’s guide to conditionals covers both forms.
When does switch make the alternatives clearer?
Use switch when one expression is compared with several discrete values and each value selects an action. Keeping the cases together makes the set of alternatives easy to scan.
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switch (action) {
case "save":
saveDocument();
break;
case "print":
printDocument();
break;
default:
showHelp();
}Here, every branch dispatches on action. The default clause handles a value that matches no case. A switch is not a substitute for arbitrary predicates or range checks; it is equality-based multiway branching. See MDN’s JavaScript language overview.
What does JavaScript switch do with cases?
JavaScript evaluates the switch expression, then selects the first case expression that matches it using strict equality (===). After selecting a case, execution continues through subsequent statements until it reaches break, another control-flow exit, or the end of the switch. That continuation is called fall-through: without an exit, later case statements run even when their labels did not match.
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Use break to prevent accidental fall-through
In the earlier example, each action ends with break, so executing one case does not run the next case’s statements. Remember that case matching does not coerce types: for example, a numeric value does not match a string containing the same digits.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsGroup cases only when they intentionally share work
switch (role) {
case "admin":
case "editor":
allowEdit();
break;
default:
denyEdit();
}Both labels intentionally lead to allowEdit(). Make that grouping clear, and use an exit after the shared action. The ESLint no-fallthrough rule is designed to flag unintended fall-through and is included in ESLint’s recommended configuration. The MDN switch reference describes case matching and control flow in detail.
Would a conditional operator be simpler?
For a simple two-way choice that produces one of two values, a conditional operator can be more concise than assigning through if...else:
const label = isReady ? "Ready" : "Waiting";Prefer it when the condition and both results are easy to understand at a glance. If the branches contain substantial logic, or a conditional operator would need nesting, use a form that keeps the decision readable. MDN’s JavaScript style guidance recommends the conditional operator for choosing a literal value, including a returned value.
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Is switch faster than if...else?
There is no universal speed winner established by the official documentation cited here. The choice should usually reflect which form makes the logic clearest. If performance is a real concern in your application, benchmark representative code in the runtime and workload that matter to you rather than relying on a branch-count rule or general speed claim.
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A practical way to choose
- Different predicates, ranges, or conditions using multiple variables: use
if...else. - One expression matched against several exact alternatives: use
switch. - A straightforward choice between two results: consider a conditional operator.
- A switch case that should not continue into the next one: end it with
breakor another clear control-flow exit.
The number of branches alone is not a reliable threshold. MDN describes if...else as suitable for a couple of choices with complex conditions, and switch as useful for selecting among many choices based on one input value. Let the structure of the decision—not an arbitrary count—guide the syntax.
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