Main Tips on Using JavaScript break For Loops And Switches

When using JavaScript, you will often run into situations where you will have to use a loop. Part of the ability to work with loops and switches is being familiar with break and continue statements. In this tutorial, you will learn about their meaning and possible usages.

JavaScript break and continue statements are especially important when working with switch statements. Yet, you should know them when working with loops as well. You will also learn about label reference, used with break and continue statements.

JavaScript break and continue: Main Tips

• The JavaScript break statement stops a loop from running.
• The continue statement skips one iteration of a loop.
• These statements work on both loops and switch statements.
• Both break and continue statements can be used in other blocks of code by using label reference.

break

The break statement stops executing a loop when a defined condition is met and continues running the code following the loop. In the example below, you can see the implementation of JavaScript break for loop:

for (i = 0; i < 15; i++) {
    if (i === 5) { break; }
    text += "Number: " + i + "<br>";
}

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continue

The JavaScript continue statement stops the current iteration of the loop when a specified condition is met and proceeds the loop with the next iteration. Basically, it skips a defined iteration.

The example below skips the value of 5:

for (i = 0; i < 15; i++) {
    if (i === 5) { continue; }
    text += "Number: " + i + "<br>";
}

Label Reference

break and continue statements are usually used in loops and switch statements. However, they can be used within any block of code. In such cases you must use a label as shown below:

break labelname;

continue labelname;

In the example below, you can see a label reference used with a break JavaScript statement in a block of code. Here, the display of the list stops after displaying the first three items:

var phones = ["iPhone", "Samsung", "Nokia", "Motorola"];

list: {
  text += phones[0] + "<br>"; 
  text += phones[1] + "<br>"; 
  text += phones[2] + "<br>"; 
  break list;
  text += phones[3] + "<br>"; 
}

Here you can see a label reference used with a JavaScript continue statement in a nested for loop. A continue statement is located within a for loop labeled Loop2. It is nested within another for loop named Loop1.

When j is equal to 7, the continue statement will make the loop skip this iteration, and make the Loop2 continue on iterating:

var text = "";
var i, j;

Loop1: // first loop
for (i = 0; i < 5; i++) {
text += "<br>" + "i = " + i + ", j = ";

  Loop2: // second loop
  for (j = 6; j < 10; j++) {
    if (j === 7) {
      continue Loop2;
    }
    document.getElementById("example").innerHTML = text += j + " ";
  }
}

Note: labels are not very common, so you shouldn't overuse them.

JavaScript break and continue: Summary

• You may use JavaScript break for loops to stop them from running after a certain condition is met.
• The JavaScript continue statement skips an iteration and makes a loop continue afterwards.
• These statements work on both loops and switch statements.
• By adding a label reference, both of these statements can be used on other blocks of code.