javascript interactive

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- An
**expression**is a calculation or operation that results in a value. Except for variable declarations, everything until now have been expressions. - A
**statement**is any construct permitted by the language, including an expression. A JavaScript program consists of a sequence of statements, all separated from each other.

>>>

a = 1; b = a + 1;

>>>

{ 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

2

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.

>>>

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