JavaScript – Exercise 11 – The Do-While Loop

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In this example, you will learn about a different kind of JavaScript loop control structure. All other loops do not let the loop execute if the condition of the loop is false. However, the do-while loop make sure that the loop execute at least once before it fails.

Structure of do-while loop

int i = 10;

do {
    
       execute statements;
       
     } while (i < 10);

In the example above the loop executes at least once before the i = 11. For the sake of do-while example. We will do the following things.

  • Create an HTML page.
  • Write JavaScript code that will sum all the elements of a two dimensional array.
  • Output the result in browser console.

HTML Example: do-while.html

Open any text editor and write the following code and save it as do-while.html.

<!DOCTYPE html>
<html>
<head>
    <title>JavaScript - Do-While Loop </title>
</head>
<body>


</body>
</html.

At this moment do not add anything in the body section. Leave it empty. Save the document as do-while.html .

Add JavaScript Code

In this section, you will add your JavaScript code to the HTML file created previously. Add the following code in the body section of the HTML document.

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  function myArrTotal(arr) {      

       var sum = 0;       
       var i = 0;       
       
             do {                
                          for(var j=0;j < arr[i].length;j++)                 
                            {                         
                                       sum = sum + arr[i][j];                 
                               }                  
                           i++;                        
                   }while(i < arr.length); 
                  return sum;
                } 
console.log("Sum =" + myArrTotal([[2],[4],[5]]));

Output : do-while loop

Output – Do-While Loop
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