Variables

> var someNumber = 42;

• someNumber is a variable we set to 42.
• Use var keyword whenever you want to create a new variable.
• In JavaScript, it's conventional to give variable names that start with lowercase letter, followed by capitalizing the first letter of subsequent words. This is called camelcase.

Variables Practice

//For reference
> var num1 = 42;   //assigns 42 to num1
> var num2 = 12;   //assigns 12 to num2
> var num3 = num1 + num2;  //adds num1 and num2 and assigns it to num3.  
> var num4 = num3;   //assigns num4 the value of num3.
> num1 = 21;         //num1's new value is 21. 
> num1;            //This will display the value of num1 (21) to the console.

1. Create a variable called someNumber and set it equal to 100.
2. Create a variable called favoriteNumber and set it equal to your favorite number.
3. Create another variable called avisFavorite and set it to 21.
4. Subtract your favorite number from mine and assign it to someNumber. 
5. Create a variable called finalNumber and set it equal to 25 times someNumber.
6. Display someNumber to the console.
7. Display finalNumber to the console. 

Methods Continued

Method Practice

//For reference

> 456.2356.toFixed(2);   //Will display "456.24"
> 123.123.toPrecision(5); // Will display "123.12"
> 135.6236.toExponential(); //Will display "1.356236e+2"

/*The values returned by the methods are strings. I will explain strings (characters inside quotes) 
in the next slide. For now, if you stored the string value returned by the methods above into 
a variable, you will need to convert that value into a number. 
e.g. a = "123";            //a is being assigned a string, not a number.  
     a = parseFloat(a);    //this will convert the string to a number. Now you can call number methods on this. 
*/

1. Convert the following to exponential notation:
   • 4569.234 
2. Convert it back.
3. Have the number set to one decimal place.
4. Repeat 1-3 for a variable set equal to any number you choose. 

Strings Continued

String Practice

1. Set a variable equal to a string that is a greeting to your best friend.
2. Call a method on that variable.
3. Set another variable with a string in all uppercase.
4. Call down toLowerCase() on the previous variable.
5. Use Concat() to concat the two previous variables. 
6. Now concatenate them using the shortcut.
7. Find the character at the third position in either of the variables. (Hint: counting is off by one)
8. Try out a few other methods from: https://goo.gl/UZBEqn

//For Reference
> var ct = "coding temple";  //this will assign "coding temple" to variable ct.
> var hw = "hello world";    //this will assign "hello world" to variable hw.
> ct.toUpperCase();          //this will return "CODING TEMPLE". It will NOT change the value of ct.
> hw.concat(ct);             //this will return "coding templehello world".  It combines two strings together.
> hw + " " + ct;             //this will return "coding temple hello world". It does the same as above, but adds a space between.

Functions Continued

> var favoriteSong = prompt("What is your favorite song?"); //I'll type "Barbie Girl"
> favoriteSong;
"Barbie Girl"

• The prompt function asks the user for an input.
• The response from the user is returned as a string from the function.
• That response is then assigned to a variable. 

Functions Practice

1. Use alert() to pop up a dialog box with a warning for the user. The warning message can be anything.
2. Use confirm() to ask a yes or no question.
3. Use prompt() to ask a question. 
   • save the response to a variable and then run any string method of your choice on it (e.g. toUpperCase())

Writing Functions Continued

> var add = function(num1, num2){ return num1 + num2; };
> add(2, 3);

• The return keyword returns the result from the function. Without it, JavaScript will return undefined. 

1. We call the add function with arguments 2 and 3.
2. The parameters num1 and num2 are set to the values passed in. num1 = 2 and num2 = 3. 
3. The code within the function is run. In this case, 2 + 3 is run. 
4. The result is then returned.

Writing Functions Practice

//For reference
> var add = function(num1, num2){ return num1 + num2; };
> add(2, 3);

1. Prompt the user for a name and return a greeting to them. e.g. "Hi Legolas!"
2. Return the difference between two numbers
3. Return the product of two numbers.
4. Return the square of number.
5. Return the cube of a number. 

Where to go from here?

Codecademy

Where to go from here?

Coursera

(starts November 2015)

Where to go from here?

Khan Academy

Where to go from here?

JavaScript and JQuery: Interactive Front-End Web Development

Where to go from here?

Coding Temple

Intermediate JS Workshop