Difference Between label and break in JavaScript

The labels and the break statement are used within loops and control flow structures to enhance flexibility and manageability. Each serves distinct purposes and can be applied in the various scenarios based on the needs of the code.

These are the following topics that we are going to discuss:

What is a Label?

A label in JavaScript is an identifier followed by a colon (:) that is applied directly before a statement. It allows to name the loops or blocks of code so that we can refer to them explicitly from other parts of your program.

Syntax:

outerLoop: for (...) 
{ 
... 
}	

Characteristics:

• Labels are used to the mark specific points in the code.
• They consist of an identifier followed by the colon (:) such as the" labelName:".
• The Labels are typically used with the loops and nested blocks to provide the target for the break or continue statements.

Applications:

• Nested Loops: The Labels are commonly used to break out of the nested loops or continue from the specific points within the loop.
• Error Handling: The Labels can be used in conjunction with the loops to implement custom error handling or retry mechanisms.

Example: outerLoop and innerLoop are labels marking the for the loops. The break outerLoop statement terminates both the loops when the inner loop condition j === 1 is met.

outerLoop: for (let i = 0; i < 3; i++) {
    innerLoop: for (let j = 0; j < 3; j++) {
        console.log(`i: ${i}, j: ${j}`);
        if (j === 1) {
            // breaks out of both the 
            // loops when j equals 1
            break outerLoop;
        }
    }
}

i: 0, j: 0
i: 0, j: 1

What is break?

The break statement in JavaScript is used to the terminate the current loop or switch statement and transfers control to the statement immediately following the terminated statement.

Syntax:

or (...) 
{ 
if (confition) break;
 }

Characteristics:

• It can be used inside loops and switch statements.
• When executed break interrupts the loop or switch and continues execution after the loop or switch.
• It can be combined with the labels to the break out of the nested loops or specific blocks of code.

Applications:

• Loop Termination: The break is used to exit a loop prematurely based on a condition.
• Switch Statement: The break is used to the terminate each case block in the switch statement to the prevent fall-through behavior.

Example: The loop iterates from the 0 to 4. When i equals 2 the break statement terminates the loop immediately.

for (let i = 0; i < 5; i++) {
    console.log(i);
    if (i === 2) {
        // stops the loop when i equals 2
        break;
    }
}

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Difference Between label and break in JavaScript

Conclusion

The Labels and the break statement are essential features in JavaScript that facilitate structured and efficient control flow. The Labels provide named targets within the code blocks allowing for the precise control over nested loops or custom error handling. On the other hand, break terminates loops and switch statements based on the conditions enabling flexible execution paths within JavaScript programs.

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Article Tags :

• JavaScript
• Web Technologies