Exercises: JavaScript Strings

Standard Exercises

0. What does this code print out? (Validate your result by typing it in the editor).

var title = "My Awesome Webpage";
console.log( "Page Title: " + title );

1. And what does this code print out? (Validate your result by typing it in the editor).

var studentName = "Emily";
var studentHeight = 150;
console.log( studentName + " is " + studentHeight + "cm tall" );

2. And what does this code print out? (Validate your result by typing it in the editor).

var studentName = "Alexander";
console.log( studentName.charAt(0) );

3. Create a string variable called firstName containing your first name and print the length of your name using firstName.length.

4. Create a second variable containing your last name and then create var fullName by concatenating your first and last name together (include a space between the names). Print your full name to the console.

5. Print the string "Your height is: X" where X is the value of the variable ‘height’ below.

var height = 120;
console.log(...);

6. Convert 'name' to UPPERCASE and print that to the console. (Tip. Check back for the functions available on a string).

var name = "Alice";
console.log( ... ); // ALICE

7. Write the function textStartsWithA(text) that returns true if the supplied parameter starts with the letter ‘A’ else return false. Test it with the following code.

console.log( textStartsWithA("Alex") );   // true
console.log( textStartsWithA("Betty") );  // false

8. Write the function containsLetter(text, letter) that returns true if "text" contains the letter described in "letter" otherwise it should return false. Test it with the following code.

console.log( containsLetter("Erika", "T") );    // false
console.log( containsLetter("Francis", "s") );  // true

9. Write a script which replaces all spaces in your full name with dashes '-' and print the result to the console. Note that the string.replace() function returns a new string but does not modify the original.

10. Print characters 0, 4 and 8 from the string ‘alphabet’ below;

var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

Advanced Exercises

11. Extract the word 'mad' from this string using the substr(start, length) method.

var fullText = "He was a mad scientist";
var mid = fullText.substr(…);
console.log(mid);    // Should print "mad"

12. Write a function to take the first 3 letters from a given string and place them on the end of the string.

console.log(rotateString("Hello"));    // Should print loHel

13. Write the function getFileExtension(text); that prints the file extension for a given filename. ie. For "index.html" it should print "hmtl". You will probably want to use ‘find’ and ‘substr’ to do this.

console.log(getFileExtension("index.html"));    // Should print "html"
console.log(getFileExtension("photo.jpg"));     // Should print "jpg"

14. Write the function pyWord that prepends the letters "Py" to a word but only if it doesn’t already start with Py.

console.log(pyWord("Wizard"));          // Should print "PyWizard"
console.log(pyWord("PyMonkey"));        // Should print "PyMonkey"

15. Write the function isEmail(text); that takes a string and returns ‘true’ if it’s a valid email address or false otherwise. Tip. You should check whether the string contains an "@" symbol and, later on, a dot ‘.’.

console.log( isEmail("john@gmail.com") );       // Should print true
console.log( isEmail("johngmail.com") );        // Should print false
console.log( isEmail("john@gmail") );           // Should print false

16. Spot the error in this code. Try running it to see the error. Once you have found the error - have a think about how you might fix it.

var name = "John";
var result = 3 + ". " + name;