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THE JAVASCRIPT COOKBOOK by Erica Sadun, webrx@mindspring.com
J. Brook Monroe, mrprogguy@techie.com
Copyright (c)1998 by Charles River Media. All Rights Reserved.
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<HEAD>
<TITLE>Reversing an Array</TITLE>
</HEAD>
<SCRIPT LANGUAGE="JavaScript1.2"><!--
var myArray;
function Go()
{
var i;
for(i = 0; i < 8; i++)
myArray[i] = eval("document.forms[0].slot"+i+".value");
myArray.reverse();
for(i = 0; i < 8; i++)
eval("document.forms[0].out"+i+".value='"+myArray[i]+"'");
}
function Warning(cellId)
{
eval("document.forms[1].out"+cellId+".value=''");
alert("No, you shouldn't type in that cell!");
}
myArray = new Array(8);
//-->
</SCRIPT>
<BODY>
<FONT COLOR="007777"><H1><IMG SRC="../GRAFX/UTENS.JPG" WIDTH=80 HEIGHT=50
ALIGN = LEFT>Reversing an Array</H1></FONT>
<BLOCKQUOTE><FONT COLOR="770000">
In this recipe we find out that JavaScript in Navigator can reverse arrays for us.
</FONT><P>
Fill in the top row of boxes and press the "GO!" button.<BR>
<FORM>
Original:<BR>
<INPUT TYPE="text" VALUE="" NAME="slot0" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot1" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot2" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot3" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot4" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot5" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot6" SIZE=8>
<INPUT TYPE="text" VALUE="" NAME="slot7" SIZE=8>
<INPUT TYPE="button" VALUE="GO!" onClick="Go()"><BR>
Reversed:<BR>
<INPUT TYPE="text" VALUE="" NAME="out0" SIZE=8 onChange="Warning(0)">
<INPUT TYPE="text" VALUE="" NAME="out1" SIZE=8 onChange="Warning(1)">
<INPUT TYPE="text" VALUE="" NAME="out2" SIZE=8 onChange="Warning(2)">
<INPUT TYPE="text" VALUE="" NAME="out3" SIZE=8 onChange="Warning(3)">
<INPUT TYPE="text" VALUE="" NAME="out4" SIZE=8 onChange="Warning(4)">
<INPUT TYPE="text" VALUE="" NAME="out5" SIZE=8 onChange="Warning(5)">
<INPUT TYPE="text" VALUE="" NAME="out6" SIZE=8 onChange="Warning(6)">
<INPUT TYPE="text" VALUE="" NAME="out7" SIZE=8 onChange="Warning(7)">
</FORM>
<FONT COLOR="007777"><H2>Discussion</H2></FONT>
<FONT SIZE=4>
Everything you need to know about this capability can be summed up in two code fragments. Which would you rather write?
<H3><FONT COLOR="007777">The Hard Way</FONT></H3>
<FONT COLOR="770000"><PRE>
function Reverse(anArray)
{
var len = anArray.length;
var tempArray = new Array(len);
var i;
var j = len - 1 ;
for(i = 0; i < len; i++) {
tempArray[i] = anArray[j];
j -= 1;
}
return tempArray;
}
</PRE></FONT>
<H3><FONT COLOR="007777">The Easy Way</FONT></H3>
<FONT COLOR="770000"><PRE>anArray.reverse();</PRE></FONT>
Perhaps we've tried to sway you by calling one the hard way and one the easy way, but we think we'll get little argument
that letting the JavaScript engine do it is the preferred method.
</FONT>
<BR><BR><h5>Copyright ©1998 by Charles River Media, All Rights Reserved</h5>
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