Use if...else for different conditions, ranges, or compound logic; use switch when one value is matched against several discrete alternatives. The choice is about how clearly each construct expresses the decision—not a fixed number of branches. For a simple choice between two results, a conditional operator may be clearest.
Choose by the shape of the decision
| Use | When it fits | What to watch |
|---|---|---|
if...else |
Branches test different predicates, ranges, multiple variables, or compound boolean conditions. | Checks run in order, so overlapping predicates make order meaningful. Long or deeply nested chains can be difficult to follow. |
switch |
One expression is compared with several discrete values, and a visible list of alternatives is easiest to scan. | Matching uses strict equality, and execution can continue into later cases if a case does not exit. |
| Conditional operator | A compact two-way choice produces one of two values or results. | Nested or elaborate ternaries can be harder to read than explicit branches. |
There is no universal branch-count threshold at which one construct becomes preferable. MDN describes if...else as useful for a couple of choices involving substantial code or complex conditions, and switch as helpful when selecting among many choices based on one input value. Treat that as guidance about the logic’s shape, not a mechanical rule. MDN’s guide to conditionals explains the distinction.
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Use if/else for ranges and predicates
When each branch tests a condition rather than a particular value, an ordered if...else chain makes that logic direct:
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label = "warm";
}The first true condition wins. Here, the checks describe ranges: below zero, then below 20, then everything else. A switch case list is not a general substitute for these comparisons. Keep overlapping conditions in the intended order, and consider simplifying or extracting logic if a chain becomes difficult to understand.
#1 Best Overall
Use switch for discrete alternatives on one value
When several outcomes depend on the same expression taking one of a set of discrete values, a switch groups the alternatives in one place:
switch (action) {
case "save":
saveDocument();
break;
case "print":
printDocument();
break;
default:
showHelp();
}default handles values that match no case. A switch evaluates its input and selects the first case whose expression matches it using strict equality; it does not test arbitrary boolean predicates or ranges. See MDN’s JavaScript switch reference and its JavaScript language overview.
Rank #2
Prevent accidental switch fall-through
After a matching case is selected, JavaScript executes statements from that point until it reaches break, another control-flow exit, or the end of the switch. Without an exit, execution continues into the next case—even if that next case’s value did not match. This is fall-through.
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switch (role) {
case "admin":
case "editor":
allowEdit();
break;
default:
denyEdit();
}Both labels reach allowEdit(); the break then prevents execution from continuing into default. Otherwise, add a clear exit after each case. ESLint’s no-fallthrough rule is designed to flag accidental fall-through and is included in its recommended configuration.
Use a ternary for a simple two-result choice
When a condition selects one of two values, the conditional operator can express that result without assigning it through an if...else block:
Rank #4
const label = isReady ? "Ready" : "Waiting";MDN’s JavaScript code-style guide recommends this form for choosing a literal value, including a returned value. Prefer explicit branching if the alternatives require substantial logic or if the expression becomes hard to scan.
Do not choose based on assumed speed
The cited official guidance explains how these constructs behave and where they fit; it does not establish that switch or if...else is universally faster. Do not trade away clarity based on a branch-count rule or a general speed claim. If performance matters in your application, benchmark representative code in its actual runtime and workload.
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