学步园

The Break Statement

The break statement can be used to jump out of a loop or a switch() statement.

The break statement breaks the loop and continues executing the code after  the loop (if any):

Example

for (i=0;i<10;i++)
   {
   if (i==3)
     {
     break;
     }
   x=x + "The number is " + i + "<br>";
   }

The Continue Statement

The continue statement breaks one iteration (in the loop), if a specified  condition occurs, and continues with the next iteration in the loop.

This example skips the value of 3:

Example

for (i=0;i<=10;i++)
  {
  if (i==3) continue;
   x=x + "The number is " + i + "<br>";
   } 

JavaScript Labels

As you have already seen, in the chapter about the switch statement, JavaScript statements  can be labeled.

To label JavaScript statements you precede the statements with a colon:

label: statements

The break and the continue statements are the only JavaScript statements that  can "jump out of" a code block.

Syntax:

break labelname;
continue labelname;

The continue  statement (with or without a label reference) can only be used inside a loop.

The break statement, without a label reference, can only be used inside a loop  or a switch.

With a label reference, it can be used to "jump out of" any  JavaScript code block:

Example

cars=["BMW","Volvo","Saab","Ford"];
list: 
{
document.write(cars[0] + "<br>"); 
document.write(cars[1] + "<br>"); 
document.write(cars[2] + "<br>"); 
break list;
document.write(cars[3] + "<br>"); 
document.write(cars[4] + "<br>"); 
document.write(cars[5] + "<br>"); 
}