Ternary Operator

The ternary operator a is a very compact, 0:00 two-way branch that many programmers use to write very concise code. 0:03 The only problem is, is that it's so compact it can be hard to read. 0:09 It's called ternary because it involves three expressions. 0:13 The first is a boolean that determines which of the next two expressions run. 0:17 The ternary operator uses two characters, a question mark and a colon. 0:23 These two characters are markers for our condition and our two branches. 0:29 Let's see how this works in our two.js file from earlier. 0:35 First, let's write our ternary operator, a question mark and a colon. 0:39 I'll show you how this works just by copying/pasting from this 0:46 if statement above. 0:50 Let's take the condition, which is stored in the variable isTrue, 0:53 and paste it before the question mark. 0:57 If isTrue evaluates to true, then the code after the question mark will run. 1:00 If not, the code after the colon will run. 1:09 So let's copy and paste the true branch, and 1:13 paste it just after the question mark here. 1:19 And copy and paste the full branch here at the end. 1:25 Don't forget to terminate your statement with a semicolon. 1:30 Now, if we comment out our if else statement, 1:34 we can see the ternary operator in action. 1:39 If we run node two.js in the command line, we get yes log. 1:46 If we change isTrue to false and 1:53 run it again, we see no is logged. 1:56 You can see that the ternary expression is almost exactly like 2:00 an if else statement, but with a bare bones syntax. 2:05 But there is another way you're likely to see a ternary pop up in the wild. 2:10 As an expression. 2:15 In JavaScript and expression is something that resolves to a value. 2:16 You can assign an expression to a variable and that variable will contain the value. 2:21 For example, you can assign var x to equal 2 + 5. 2:26 2 + 5 is an expression that resolves to the value of 7. 2:34 X isn't going to hold 2 + 5, 2:40 it's going to hold the value that the expression returns, which is 7. 2:43 In the same way, a ternary expression will return one of it's 2:47 two branches as a value, depending on the truthiness of the first operand. 2:52 Let's see this in the code to get a better idea. 2:58 Instead of logging yes or no to the console directly from the ternary, 3:02 let's return one of those values and store it in a variable called yesOrNo. 3:06 Then we can log that variable to the console, 3:22 When the ternary is a evaluated by the interpreter, 3:30 it examines the value of isTrue and 3:34 returns the first value of yes if it's true, and no if it i not. 3:37 And it's choice will be stored in yesOrNo. 3:43 Let's save it and run it again. 3:48 Now let's change it to true and run the script again. 3:52 Technically, you could use the ternary for a multi-way branching while putting 4:00 one expression as the condition for the larger ternary expression. 4:05 But this gets messy real quick, and it's not a recommended practice. 4:10 If you ever use the ternary expression, it should probably be for 4:15 very simple cases where the intent is unmistakable and obvious. 4:20 For our last conditional, let's have a look at short circuiting. 4:25 I'll see you in the next video. 4:29