Web Programming with HTML5, CSS, and JavaScript

10.9 for Loop

In the previous section, we used a while loop to access all the checkboxes in the collection of job skills checkboxes. Using a while loop works OK, but in this section, we use a for loop to access the checkboxes, which leads to a more compact implementation.

FIGURE 10.13 shows the while loop used in the Job Skills web page and a functionally equivalent for loop. Both versions use a counter variable, i, that gets initialized to 0 and gets incremented each time through the loop. With a for loop, the counter mechanism is implemented within the loop’s heading. It’s such a foundational part of a for loop that the counter variable is given a special name—an index variable. Sound familiar? Yep, an index variable is also the name we ...