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If...else statements

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So far, you've seen how you can use logical operators as part of an assignment. Another common use for operators is as part of if/else constructs.

If statement

The if statement runs code in between its blocks if the condition is true. The condition within the if clause can either be a value that contains a truthy value or a conditional statement that evaluates to true. The following code shows how you express an if clause.

if (condition){
    //Condition was true. Code in this block will run.
}

Compare a value

You can pass a variable or a Boolean value to an if clause like so:

let isTrue = true;
if (isTrue) {
  // run code if true
}

if (true) {
  // run code if true
}

Use a logical operator

Logical operators are often used to form the condition. You need three things: a value, a comparison operator that shows how you want to compare, and a value to compare to. The syntax looks like the following code:

if (value operator compareToThisValue) {
  // run code
}

Here's an example that uses the preceding syntax to compare variables' values by using a larger-than (>=) operator:

let currentMoney = 1000;
let laptopPrice = 1500;

if (currentMoney >= laptopPrice){
    //Condition was true. Code in this block will run.
    console.log("Getting a new laptop!");
}

Tip

As a developer, you need to get used to reading code and understanding how it will execute. Take a short break here, and try to figure out if the code within the if clause will execute or not.

Because the value of currentMoney is lower than the value of laptopPrice, the statement within the if clause will evaluate to false. The statement within the if clause won't run.

If...else statement

The else statement will run the code in between its blocks when the if condition evaluates to false. Using else is optional.

let currentMoney = 1000;
let laptopPrice = 1500;

if (currentMoney >= laptopPrice) {
    //Condition was true. Code in this block will run.
    console.log("Getting a new laptop!");
} else{
    //Condition was true. Code in this block will run.
    console.log("Can't afford a new laptop, yet!");
}

Tip

Test your understanding of the preceding code by running it in a browser console. Change the values of the currentMoney and laptopPrice variables to change the returned console.log().

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