# If and Else Statements in JS

by **Nathan Stockton**, adapted for JS by [kirupa](https://www.kirupa.com/me/index.htm) | 13 December 2011

If and else statements are some of the more commonly used words in not only JavaScript but most modern programming languages. They fall under an umbrella of concepts that use terms such as ***conditionals*** or ***boolean logic***. The terminology is not as important as what they actually do. They help your code decide between two or more potential paths. They have a basic principle, which is, if * **statement one*** is true to ***statement two***, then run the following code before the **if** is closed.

So their format is:

if (statement_one operator statement_two){

That is not too clear, solely because of the *** operator*** part...which I haven't explained yet. The operator is what you use to compare/check statements one and two with. The operators you can use in JavaScript and what they do are listed below in terms of `var1` and `var2`:

The above table lists the most common operators you will use. Now, it is time to explain how to use them. For the following examples, we will assume that variable_1 and variable_2 are values and have been initialized earlier.

If, for example, you wanted to check if variable_1 is greater than variable_2 you would use the following fragment of code:

Similarly, to check if both variables are equal, you would use:

Let's say variable_1 is now equal to the string **foo**. If you are checking if variable_1 is equal to the string ** foo**, you will need to use quotation marks on the foo to designate it as a string:

The == operator when applied to strings cares about capitalization. So "Foo" is not equal to "foo". If you want to check if the characters are the same, you can do a toUpperCase or toLowerCase on the text and then do the compare.

In the above statement, I check if variable_1 is equal to variable_2 and also check if variable_3 is greater than variable_4. Notice the order of operations does not check if variable_2 and variable_3 exist, even though at first glance it could look like that could be the case.

That is why it is recommended to use many parentheses to improve readability:

Up until now, we have code that executes when the if statement is true. There will be cases, in fact almost always, when you want something to execute if the statement is false. Thus, this is where the **else** statement comes into play:

In the above code, if variable_1 is not equal to foo, the code in the else statement will execute instead. Of course, to take this one step further, you can have multiple statements by extending **else** and **if** and getting **else if**. Else if allows you to have several if statements that evaluate in order as shown in the following code fragment:

In the above code fragment you check if variable_1 is equal to 80, and if it is, you exit your code fragment and execute the code for the equal statement. If variable_1 does not equal 80, instead of jumping straight to the **else** statement, you stop at the **else if** statement and check if variable_1 is greater than 80 instead. Only if you fail again do you go to **else** for there is no where else for you to go!

So with this, I think you have a good idea of what you can do using **if** and **else** statements. They are quite fundamental for most programs, so it is good to be familiarized with them to a point where you don't spend too much time thinking about them.

#### **Note**

You can use a short-hand version of all of the if/else statements if you so choose. [ Swooter's post](https://www.kirupa.com/forum/showthread.php?370053-Tutorial-If-and-Else-Statements-in-JS&p=2630113&viewfull=1#post2630113) provides a nice summary of them.

If you have any questions, feel free to post on the [kirupa.com forums](https://www.kirupa.com/forum/).

Cheers!

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