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6.20 Summary of JavaScript Statements

This chapter introduced each of the statements of the JavaScript language. Table 6-1 summarizes these statements, listing the syntax and purpose of each.

Table 6-1. JavaScript statement syntax

Statement

Syntax

Purpose

break
break;

break labelname;

Exit from the innermost loop or switch statement or from the statement named by label.

case
case expression:

Label a statement within a switch statement.

continue
continue; 

continue labelname;

Restart the innermost loop or the loop named by label.

default
default: 

Label the default statement within a switch statement.

do/while
do

    statement

while (expression);

An alternative to the while loop.

empty
;

Do nothing.

for
for (initialize ; test ; increment)

    statement

An easy-to-use loop.

for/in
for (variable in object)

    statement

Loop through the properties of an object.

function
function funcname([arg1[..., argn]]) {

    statements

}

Declare a function.

if/else
if (expression)

    statement1

[else statement2]

Conditionally execute code.

label
identifier: statement

Give statement the name identifier.

return
return [expression];

Return from a function or return the value of expression from a function.

switch
switch (expression) {

    statements

}

Multiway branch to statements labeled with case or default: .

throw
throw expression;

Throw an exception.

try
try {

    statements

}

catch (identifier) {

    statements

}

finally {

    statements

}

Catch an exception.

var
var name_1 [ = value_1]

[ ..., name_n [ = value_n]];

Declare and initialize variables.

while
while (expression)

    statement

A basic loop construct.

with
with (object)

    statement

Extend the scope chain. (Deprecated.)

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