How to use Loop?
Loops are useful when you have to execute the same lines of code repeatedly until a specific condition is corrected. Suppose you want to type the message ‘Hello’ 100 times in your webpage. Of course, you have to copy and paste the same line 100 times. Instead, if you use a loop, you can complete this task in only 3 or 4 lines. || For While and Do While LOOP in JavaScript
Different Types of Loops
There are mainly four types of loops in JavaScript.
- for loop
- for/in a loop (explained later)
- while loop
- do…while loop
for loop
Syntax:
for(statement1; statement2; statment3)
{
lines of code to be executed
}
- The statement1 is executed first even before executing the looping code. So, this statement is normally used to assign values to variables that will be used inside the loop.
- The statement2 is the condition to execute the loop.
- The statement3 is executed every time after the looping code is executed.
Try this yourself:
while loop
Syntax:
while(condition)
{
lines of code to be executed
}
The “while loop” is executed as long as the specified condition is true. Inside the while loop, you should include the statement that will end the loop at some point of time. Otherwise, your loop will never end and your browser may crash.
Try this yourself:
do…while loop
Syntax:
do
{
block of code to be executed
} while (condition)
The do…while loop is very similar to while loop. The only difference is that in do…while loop, the block of code gets executed once even before checking the condition.
Try this yourself: