trying to "cycle" the value of a variable

@Michael_BlissOct 23.2011

Hi I’m trying to write some code to cycle the value of my universal variable window.BodyPart (BodyPart) being passed to the function when it’s called (onclick event of imagemap). For example onclick=AddMassinst(‘shoulder’), then using window.shoulder by refering to it through window.BodyPart (is that right or is my syntax all messed, or is that even possible?)

Here’s my code, I’m expecting window.BodyPart to cycle through blank, a, b, c, then blank (undefined) again. I’m very new to this so please forgive my ignorance.

function AddtoMassInst(BodyPart)

{
alert(window.BodyPart)

if (window.BodyPart=”)

{
window.BodyPart=’a’
}

else if (window.BodyPart=’a’)

{
window.BodyPart=’b’
}

else if (window.BodyPart=’b’)
{

window.BodyPart=’c’
}

else if (window.BodyPart=’c’)
{
window.BodyPart=”
}
else
{
alert(“else!”)
}

return true;
}

to post a comment

JavaScript

7 Comments(s) _↴

@Declan1991Oct 23.2011 — #Your problem is that "==" is the equality operator, and "=" is the assignment operator. So "if (window.BodyPart == 'c')" is what you want.

I'm not exactly sure what you mean, so if you've further problems, post again.

@vwphillipsOct 23.2011 — #

[CODE]<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 
 <head>
 <title></title>
 <script  type="text/javascript">
 /*<![CDATA[*/
 var BodyPart='';
 
 function AddtoMassInst(){
 alert(BodyPart)
 
 if (BodyPart[COLOR="Red"]==[/COLOR]''){
 BodyPart='a'
 }
 
 else if (BodyPart=='a'){
 BodyPart='b'
 }
 
 else if (BodyPart=='b'){
 
 BodyPart='c'
 }
 
 else if (BodyPart=='c'){
 BodyPart=''
 }
 else{
 alert("else!")
 }
 
 return true;
 }
 /*]]>*/
 </script></head>
 
 <body>
 <input type="button" name="" value="Test" onmouseup="AddtoMassInst();" />
 </body>
 
 </html>[/CODE]

@Michael_BlissauthorOct 23.2011 — #thanks that helped a lot! I still have one unsolved problem: what I'm trying to do is setup a global variable (I know they're bad, is there another simple way of doing this?) for each bodypart clicked on an anatmical image. The variable would contain a number of possible states that are cycled through (you helped me accomplish this already). What I want to know is do I have to declare each variable seperately outside the function, or can I pass the name of the variable via the function call (so onClick="AddBodyPart('Neck' )" or onClick="AddBodyPart('Face') would each generate their own variable window.Neck and window.Face with this code) for example?

function AddBodyPart(BodyPart)

{

alert(window.BodyPart)

if (window.BodyPart==undefined)

{

window.BodyPart=BodyPart+'a'

}

else if (window.BodyPart==BodyPart+'a')

{

window.BodyPart=BodyPart+'b'

}

else if (window.BodyPart==BodyPart+'b')

{

window.BodyPart=BodyPart+'c'

}

else if (window.BodyPart==BodyPart+'c')

{

window.BodyPart=undefined

}

else

{

alert("else!")

}

return true;

}

@JunkMaleOct 23.2011 — #anything not declared as a [COLOR="Navy"][B]var[/B][/COLOR] is global.

@Declan1991Oct 23.2011 — #I still don't get what you are trying to do, but you can certainly do this.

function addBodyPart(bodyPart) {
 if (window[bodyPart] == undefined) {
 window[bodyPart] = bodyPart + "a";
 }
 else if (window[bodyPart] == bodyPart + "a") {
 window[bodyPart] = bodyPart + "b";
 ... }
 }

This can also be done with closures, but if I don't know what you are doing this for, I can't really show a good (i.e. appropriate) example of that.

@vwphillipsOct 24.2011 — #

[CODE]<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 
 <head>
 <title></title>
 <script  type="text/javascript">
 /*<![CDATA[*/
 
 function AddtoMassInst(bp){
 var temp=window[bp]||'';
 
 if (temp==''){
 temp='a'
 }
 
 else if (temp=='a'){
 temp='b'
 }
 
 else if (temp=='b'){
 
 temp='c'
 }
 
 else if (temp=='c'){
 temp=''
 }
 else{
 alert("else!")
 }
 window[bp]=temp;
 alert(BodyPart)
 return true;
 }
 /*]]>*/
 </script></head>
 
 <body>
 <input type="button" name="" value="Test" onmouseup="AddtoMassInst('BodyPart');" />
 </body>
 
 </html>[/CODE]

@Logic_AliOct 24.2011 — #This function will return the next value in the array [FONT=Courier New]series[/FONT] if it finds [FONT=Courier New]current[/FONT] within the array, otherwise returns "".

[FONT=Courier New]myVar[/FONT] does not have to be global.

<i>
 </i>var myVar = 'cranium' ;
 
 function getNextValue( current, series )
 {   <br/>
 for( var i = 0, len = series.length; i &lt; len &amp;&amp; series[ i ] !== current; i++ )
 ;
 
 return i == len || i == series.length -1  ? "" : series[ i + 1 ];
 }
 
 myVar = getNextValue( myVar, [ 'mandible', 'metatarsal', 'clavicle', 'cranium', 'femur', 'vertabra' ] );
 
 alert( myVar );

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