javascript

CHAPTER 4 ■ CONTROLLING FLOW
falsy element from looseLeafTea by way of the predefined splice()method, which we will cover in more
detail in Chapter 5, that just removes the element from the array and then brings the subsequent
elements forward to fill the gap. Second, we will insert a continue statement to abort the iteration. This
statement will halt the current iteration of the loop and jump back to the start of the while loop with a
new iteration. Note that this means we will skip the i ++ line of code, so the counter will not be
incremented. This is exactly what we want to happen because, when we removed the falsy element,
JavaScript brought all the remaining elements forward to fill the gap, so there is a new element now
occupying the position of the old falsy element. For that reason, we want to loop over the same index in
the array twice to make sure we cover all the elements. Finally, let’s increment i within an else clause
just to make things read better.
So, modify the previous sample like so, and click Run in Firebug:
var looseLeafTea = [
"Ghillidary",
"",
"Kenilworth",
"Milima",
,
"Keemun",
"Boisahabi",
"Manohari",
"Borpatra",
"Lukwah",
"Khongea"
];
var mood = "glum";
var i = 0;
while (i < looseLeafTea.length) {
if (looseLeafTea[i] === "Borpatra") {
mood = "cheery";
break;
} else if (! looseLeafTea[i]) {
looseLeafTea.splice(i, 1);
continue;
} else {
i ++;
}
}
"I feel " + mood + "!";
// "I feel cheery!"
Before moving on, let’s check to make sure JavaScript did weed out the "" and undefined values
from looseLeafTea. So, click Clear, and then query looseLeafTea like so, verifying your work with Figure
4–9:
looseLeafTea;
// ["Ghillidary", "Kenilworth", "Milima", "Keemun", "Boisahabi", "Manohari",
// "Borpatra", "Lukwah", "Khongea"]
So there it is. JavaScript deleted the "" and undefined elements just like we wanted.
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