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Functions

Essentially, the

switch

statement prevents a developer from having to write something like this:

if (i == 25)

alert(“25”);

else if (i == 35)

alert(“35”);

else if (i == 45)

alert(“45”);

else

alert(“Other”);

The equivalent

switch

statement is:

switch (i) {

case 25: alert(“25”);

break;

case 35: alert(“35”);

break;

case 45: alert(“45”);

break;

default: alert(“Other”);

}

Two big differences exist between the

switch

statement in ECMAScript and Java. In ECMAScript, the

switch

statement can be used on strings, and it can indicate case by nonconstant values:

var BLUE = “blue”, RED = “red”, GREEN = “green”;

switch (sColor) {

case BLUE: alert(“Blue”);

break;

case RED: alert(“Red”);

break;

case GREEN: alert(“Green”);

break;

default: alert(“Other”);

}

Here, the

switch

statement is used on the string

sColor

, whereas the

case

s are indicated by using the

variables

BLUE

RED

, and

GREEN

, which is completely valid in ECMAScript.

Functions

Functions are the heart of ECMAScript: a collection of statements that can be run anywhere at anytime.

Functions are declared with the keyword function, followed by a set of arguments, and finally by the

code to execute enclosed in braces. The basic syntax is:

function

functionName

(

arg0, arg1,...,argN

) {

statements

}

ECMAScript Basics

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