2.4 Statements

>>>

var a = 1;
var b = a + 1;

A ; character is used to separate statements. Several statements can be placed on a single line, although it is commonly avoided.

>>>

{
    var a = 1;
    a += 2;
}

The { and } characters are (also) used to group several statements. This is sometimes called a block.

>>>

a = 1, b = a + 1

The , operator in expressions is similar to the ; statement separator. It evaluates both expressions, but will only return the second one. Compare with the boolean operators:

A && B — If A is true, evaluate B.
A || B — If A is false, evaluate B.
A , B — Always evaluate A and B.

>>>

The console allows you to interact with the course material and examples. Use the following keys:

<Enter> — Execute the code
<Shift + Enter> — Add line break
<Arrow-Up> — Previous command in history
<Arrow-Down> — Next command in history

A special logging function is also available:

print(value) — Prints a value to the console.
print(value, true) — Prints a debug version of a value.

Console Learner — An interactive JavaScript course.