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Iterate with JavaScript Do...While Loops

Randy Rivera
Once I truly put my mind on something, I won't ever stop.
・1 min read

The next type of loop you will learn is called a do...while loop. It is called a do...while loop because it will first do one pass of the code inside the loop no matter what, and then continue to run the loop while the specified condition evaluates to true.

  • Example:
var myArray = [];
var i = 10;

do {
  myArray.push(i);
  i++;
} while (i < 10);
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console.log(myArray); will display [ 10 ]
console.log(i); will display 11
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  • In this case, we initialize the value of i to 10. When we get to the next line, there is no condition to evaluate, so we go to the code inside the curly braces and execute it. We will add a single element to the array and then increment i before we get to the while condition. When we finally evaluate the condition i < 10 on the last line, we see that i is now 11, which fails the I < 10 so we exit the loop and are done. At the end of the above example, the value of myArray is [10]. Essentially, a do...while loop ensures that the code inside the loop will run at least once.

Discussion (2)

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dimaldim profile image
Dimitar Dimitrov

I believe you have a typo at "the value of ourArray", it should be myArray instead as you are initializing that

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rthefounding profile image
Randy Rivera Author

yes it was a typo thank you