Difference between a while and a do while loop in JavaScript give an example of when you would use each?

Welcome, aspiring ICT students, to our in-depth exploration of JavaScript loops! Today, we’ll focus on two commonly used looping constructs: the ‘while’ loop and the ‘do-while’ loop. Loops are essential in programming, enabling us to execute a block of code repeatedly until a certain condition is met. Understanding difference between a while and a do while loop in JavaScript give an example of when you would use each?. Then learn the nuances between these two loop types will help you write efficient and bug-free code.

Difference between a while and a do while loop in JavaScript

1. The ‘while’ Loop:

The ‘while’ loop is the most basic type of loop in JavaScript. It starts by evaluating a condition before executing the block of code enclosed within the loop. If the condition is true, the code block is executed, and the process is repeated until the condition becomes false. If the condition is false from the start, the code block won’t run at all.

Syntax:

vbnetCopy code<code>while (condition) {
  // Code block to be executed while the condition is true
}
</code>

Example Scenario: Suppose we want to calculate the sum of numbers from 1 to 5 using a ‘while’ loop:

javascriptCopy code<code>let num = 1;
let sum = 0;

while (num <= 5) {
  sum += num;
  num++;
}

console.log("Sum:", sum); // Output: Sum: 15
</code>

2. The ‘do-while’ Loop:

The ‘do-while’ loop is similar to the ‘while’ loop, but with one crucial difference: it executes the code block first and then evaluates the condition. This ensures that the code block is executed at least once, regardless of whether the condition is initially true or false. If the condition is true after the first iteration, the loop continues to run.

Syntax:

arduinoCopy code<code>do {
  // Code block to be executed
} while (condition);
</code>

Example Scenario: Let’s use the ‘do-while’ loop to take input from the user until they enter a positive number:

javascriptCopy code<code>let num;
do {
  num = parseInt(prompt("Enter a positive number:"));
} while (num <= 0);

console.log("You entered:", num);
</code>

Explanation: In this example, the code block inside the ‘do’ runs first, prompting the user to enter a number. The loop continues to execute as long as the entered number is less than or equal to zero. It will keep asking for input until the user enters a positive number.

Comparison:

The fundamental difference between the two loops is when the condition is evaluated. The ‘while’ loop checks the condition first before executing the code block, while the ‘do-while’ loop ensures the code block is executed at least once before evaluating the condition.

When to use each loop:

1. ‘while’ loop:
   • Use a ‘while’ loop when you want to execute a code block only if the condition is initially true.
   • The ‘while’ loop is useful when the loop may not need to run at all, depending on the initial condition.
2. ‘do-while’ loop:
   • Use a ‘do-while’ loop when you need to execute a code block at least once before evaluating the condition.
   • This loop is handy when you require user input validation or when you want to ensure a particular task executes at least once.

Conclusion:

Congratulations, ICT students, on completing this exploration of JavaScript’s ‘while’ and ‘do-while’ loops! You now understand their differences and when to use each loop type effectively. Loops are powerful tools, and mastering them will make you more proficient in solving various programming challenges. Happy coding!

Similar Articles Tagged

Articles, Code, Education, General, Article, Computer Science, Iteration, JavaScript, Programming