Using break after default in switch statement when default not at end

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In a w3schools tutorial on switch statements, it says:

If default is not the last case in the switch block, remember to end the default case with a break.

However, as that tutorial also states:

When JavaScript reaches a break keyword, it breaks out of the switch block.

So if you have a default with break at the beginning of a switch statement, why wouldn't the default always be executed and the block immediately exited by the interpreter? The interpreter doesn't read the items in the switch statement in order?

As the tutorial states

The default keyword specifies the code to run if there is no case match

The position of the default keyword doesn't matter, the cases after it will be tested before executing the code in the default case. If one of those cases match, its code will be executed, so the break in the default block won't be executed.

The code after default is only executed if none of the explicit cases match, or the case before default is chosen and there's no break before default (so it falls through).

The default: case is usually written last by convention, so a break is not normally needed there. The warning in the tutorial is just a reminder that if you put default: earlier, the rule that you continue into the next case when there's no break still applies; there's nothing special about the default rule that would prevent it.

Break on default case in switch, It's interactive, fun, and you can do it with your friends. Is the break; necessary for the default case? break not reachable after return , an break after default because this is the last thing to be executed of this switch part. see code bellow,� In a w3schools tutorial on switch statements, it says: If default is not the last case in the switch block, remember to end the default case with a break. However, as that tutorial also states: When JavaScript reaches a break keyword, it breaks out of the switch block.

This is specified in ECMA-262, 13.12.9 Runtime Semantics: CaseBlockEvaluation (that's the definition of JavaScript).

Unfortunately that specification is a bit hard to read, but it boils down to the following: To execute a switch statement, try the case clauses before default, if any; then try the case clauses after default, if any; and only if none of them match, execute the default part. It doesn't matter where the default is located.

For switch, do we need the break in default?, You can use the break statement to end processing of a particular labeled statement The default statement is executed if no case constant-expression value is equal to The following examples illustrate switch statements:. If default is not the last case in the switch block, remember to end the default case with a break. Common Code Blocks Sometimes you will want different switch cases to use the same code.

From that tutorial you can also read:

The default keyword specifies the code to run if there is NO CASE match.

So for example, if defined at the beginning, and there is a case match, the code associated with that match will be executed, and not the code associated with the default block, example:

function test(n)
{
    let res;

    switch (n)
    {
        default: 
            res = "default";
            break;
        case 1:
            res = "Case 1";
            break; 
        case 0:
            res = "Case 2";
     }

     return res;
}

console.log(test(1), test(0), test(9));
.as-console {background-color:black !important; color:lime;}
.as-console-wrapper {max-height:100% !important; top:0;}

switch Statement (C), the last case in a switch-case does not need a break statement, the default block In some usages you want a break at the end of default, in others, you don 't. if you have other statements in the switch body after the default you can use� It branches to the end of the switch statement. Without break, the program continues to the next labeled statement, executing the statements until a break or the end of the statement is reached. This continuation may be desirable in some situations. The default statement is executed if no case constant-expression value is equal to the value of

Why don't we use a break statement in a “default” switch case?, Note that any init-statement must end with a semicolon ; , which is why it is case: and default: labels are permitted in statement and break; constant_expression, -, a constant expression of the same type as the type of condition after Because transfer of control is not permitted to enter the scope of a� If a matching expression is found, execution can continue through later case or default labels. The break statement is used to stop execution and transfer control to the statement after the switch statement. Without a break statement, every statement from the matched case label to the end of the switch, including the default, is executed. For

switch statement, Without a break statement, every statement from the matched case label to the end of the switch statement, including the default clause, is executed. In loops, the break statement ends execution of the nearest enclosing do, for, or while statement. Control passes to the statement that follows the ended statement, if any. Within nested

We actually do sometimes. Other answers say that the default doesn't need a break because it's the last part of a switch case. While it's true that the last case in a switch-case does not need a break statement, the default block doesn't have to b

Comments
  • Because the default: case is only used if none of the other cases match.