JavaScript in Plain Language (2015)
PART II: ENTERING THE SECOND REALM
2.12 Lab work 9
NOTE: If you want to do this exercise along with me jump the next 14 steps.
Reserve this page for future practice.
1- Take the following array y as an example and sort the array:
var y = ["grape", "apple", "banana"];
2- Now assign to a new array mySort, the contents of the sorted array y.
3- Test mySort by displaying its contents on the Console.
4- Now, display the array mySort in a string type format and
split the items with 1 blank space. Hint: use join().
5- Now, instead of just displaying it, assign the items from mySort to a new variable z, but in a string format.
Use a combination of space, forward slash, and space as a separator.
6- Call z.
7- Use the indexOf() method to find the position of "banana" in array y.
8- Test for the existence of "banana" in array y ( use an if conditional statement), and display the following message on the screen using console.log():
"banana is contained in array y"
9- Using the same method as the last exercise, look for "chestnut", then
display two messages, one for if() and another for else as follows:
"chestnut is contained in array y"
else: "chestnut is not found in array y".
10- Remove the last item of array mySort using pop():
11- Remove the first item of array mySort using shift():
12- The array mySort should now only contain "banana".
Add "chestnut" as the last item.
Use push().
mySort should now have 2 items, ["banana", "chestnut"]
13- Using splice(), insert "apple" in array mySort at position 1 (as a second item). Do not delete any existing item.
mySort should now contain ["banana", "apple", "chestnut"]
14- Using slice(), create a new array named newArray with a copy of the second and third items ( "apple" and "chestnut") from mySort array.
The newArray should now contain ["apple", "chestnut"].
(See my results on the next page.)
Answers to Lab work 9:
1- Take the following array y as an example and sort the array:
var y = ["grape", "apple", "banana"];
y.sort();
It returns ["apple", "banana", "grape"]
2- Assign a new array named mySort to the contents of a sorted array y:
var mySort = y.sort();
3- Test mySort:
mySort;
It returns ["apple", "banana", "grape"]
4- Now display the array mySort is a string type format,
and split the items whit 1 blank space. Hint: use join():
mySort.join(" ");
or you might have done this which is also correct:
console.log(mySort.join(" "));
It returns "apple banana grape" in a string format.
5- Now, instead of just displaying it, assign the items from mySort to a new variable z, but in a string format. Use a combination of space, forward slash, and space as a separator:
var z = mySort.join(" / ");
6- Call z:
z;
It returns "apple / banana / grape"
7- Use the indexOf() method to find the position of "banana" in array y:
y.indexOf("banana");
It returns 1, which means that "banana" exists and is located on position1 (second item).
8- Test for the existence of "banana" in array y ( use an if conditional statement), and display the following message on the screen using console.log():
"banana is contained in array y":
if(y.indexOf("banana") >=0){
console.log("banana is contained in array y");
}
It returns "banana is contained in array y"
9- Using the same method as the last exercise, look for "chestnut".
Then display two messages, one for if() and another for else as follows:
"chestnut is contained in array y"
else: "chestnut is not found in array y":
if(y.indexOf("chestnut") >=0){
console.log("chestnut is contained in array y");
} else {
console.log("chestnut is not found in array y");
}
It returns "chestnut is not found in array y"
10- Remove the last item of array mySort using pop():
mySort.pop();
It removes "grape"
11- Remove the first item of array mySort using shift():
mySort.shift();
It removed "apple"
12- mySort should now only contain "banana".
Add "chestnut" as the last item, using push():
mySort.push("chestnut");
mySort should now have 2 items, ["banana", "chestnut"]
13- Using splice(), insert "apple" in array mySort at position 1 (as a second item) and
do not delete any existing item.
mySort.splice(1,0,"apple");
mySort should now contain ["banana", "apple", "chestnut"]
14- Using slice(), create a new array named newArray with a copy of the second and third items ( "apple" and "chestnut") from mySort array:
var newArray = mySort.slice(1,3);
The newArray now contains ["apple", "chestnut"].
The argument 1 represents the second location from mySort, and argument 3 represents the exclusion which starts at location 3.
· Yes, location 3 does not exist, but we had to cover location 2 in order to include chestnut. The exclusion started at location3, which is item 4.
It may be overwhelming at first.
Practice, practice, practice.
END OF LAB