I'm happy to share that I've officially completed week one of General Assembly's Java Immersive program. We dove into the command line, HTML/CSS and JavaScript. I haven't written in about two months so lets get right to it! I'll be going over if/else
statements to solidify my knowledge in JavaScript.
The if
statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement can be executed.
if () {}
Let's dive into the above piece of code. Within the parentheses you'll need to write a conditional expression.
if (condition) {
statement1
}
First, I've declared a variable and stored the number 400
inside of it. Next, I created an if
statement and added a condition inside of the parentheses.
let x = 400
if (x > 50) {
console.log("I'm larger than the number 50!");
}
Within the curly brackets I've gone ahead and created a statement. In this case I've written code that will show in the console ONLY if the condition returns a truthy
value.
Remember, a truthy value is a value that is considered true when encountered in a Boolean context. See below for the group of values that are considered falsy
in JavaScript. Note, all values outside of the group below are considered truthy
.
What do you think will be the output when I run the above block of code. To confirm let's head over to the browser console.
INPUT
let x = 400
if (x > 50) {
console.log("I'm larger than the number 50!");
}
OUTPUT
I'm larger than the number 50!
Since 400
is larger than 50
the statement is displayed in the console. What if I want to display a different output if the number is less than 50? How would I set that up? In this case we can add an else
statement to the above code.
let x = 41
if (x > 50) {
console.log("I'm larger than the number 50!");
} else {
console.log("I'm smaller than the number 50!");
}
Output
I'm smaller than the number 50!
The reason why we get the above output is because when the first condition was executed it resolved as falsy
.
Let's check out a real world example.
function startAdventure() {
let local = prompt('Captian Picard has a mission for you in the Delta Quadrant. Do you take along riker or data?')
if (local === "riker") {
riker();
} else if (local === "data") {
data();
}
}
Above I have a function that allows the client to navigate prompts depending on their response.
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