Can You Use Expressions in JavaScript Switch-Case Statements?

Expression-Based Switch Cases in JavaScript

In JavaScript, switch-case statements provide a convenient way to handle multiple cases based on a specific value. However, traditional switch-case statements require string or integer values to be compared. In certain scenarios, it may be desirable to use expressions that get evaluated during the comparison.

Issue Encountered

One such scenario is described by a user who encountered a challenge while attempting to use an expression within a switch-case statement:

<code class="javascript">switch (amount) {
    case (amount >= 7500 && amount < 10000):
        // Code
        break;
    // Other cases
    default:
        // Default code
}

However, this code resulted in unexpected behavior, leading to the question of whether it is possible to use expressions in switch-case statements.

Addressing the Problem

The issue arises from the fact that the amount variable is a number, while the expressions in the case clauses evaluate to booleans (i.e., true or false). As a result, the values never match, causing the code within the case clauses to never execute.

To resolve this, one approach is to enclose the expression in a true statement:

<code class="javascript">switch (true) {
    case (amount >= 7500 && amount < 10000):
        // Code
        break;
    // Other cases
    default:
        // Default code
}</code>

This works because the value being compared is now the boolean true. Consequently, the code under the first case clause with an expression that evaluates to true will execute.

Considerations

While this technique allows for the use of expressions in switch-case statements, it should be used with caution. If-else statements may be more concise and easier to read for certain scenarios. Ultimately, the choice between switch-case statements and if-else statements depends on the specific requirements of the code.

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