JavaScript Statement Identifiers

JavaScript statements often start with a statement identifier to identify the JavaScript action to be performed.

Statement identifiers are reserved words and cannot be used as variable names (or any other things).

Here is a list of some of the JavaScript statements (reserved words) you will learn about in this tutorial:

Statement	Description
break	Terminates a switch or a loop.
catch	Marks the block of statements to be executed when an error occurs in a try block.
continue	Jumps out of a loop and starts at the top.
do ... while	Executes a block of statements and repeats the block while a condition is true.
for	Marks a block of statements to be executed as long as a condition is true.
for ... in	Marks a block of statements to be executed for each element of an object (or array).
function	Declares a function.
if ... else	Marks a block of statements to be executed depending on a condition.
return	Exits a function.
switch	Marks a block of statements to be executed depending on different cases.
throw	Throws (generates) an error.
try	Implements error handling to a block of statements.
var	Declares a variable.
while	Marks a block of statements to be executed while a condition is true.

There is a complete list of reserved words, in a later chapter of this tutorial.

Sumber : w3schools