Here’s the logical expression used to represent Julia’s weekend plans:

var colt = "not busy";
var weather = "nice";

if (colt === "not busy" && weather === "nice") {
  console.log("go to the park");
}

Prints: "go to the park"

Notice the && in the code above.

The && symbol is the logical AND operator, and it is used to combine two logical expressions into one larger logical expression. If both smaller expressions are true, then the entire expression evaluates to true. If either one of the smaller expressions is false, then the whole logical expression is false.

Another way to think about it is when the && operator is placed between the two statements, the code literally reads, "if Colt is not busy AND the weather is nice, then go to the park".

Logical expressions

Logical expressions are similar to mathematical expressions, except logical expressions evaluate to either true or false.

11 != 12

Returns: true

You’ve already seen logical expressions when you write comparisons. A comparison is just a simple logical expression.

Similar to mathematical expressions that use +, -, *, / and %, there are logical operators &&, || and ! that you can use to create more complex logical expressions.

Logical operators

Logical operators can be used in conjunction with boolean values (true and false) to create complex logical expressions.

By combining two boolean values together with a logical operator, you create a logical expression that returns another boolean value. Here’s a table describing the different logical operators:

By using logical operators, you can create more complex conditionals like Julia’s weekend example.

TIP: Logical expressions are evaluated from left to right. Similar to mathematical expressions, logical expressions can also use parentheses to signify parts of the expression that should be evaluated first.