Need some with with JQuery and an if/else if statement...

MikeTheVike · 09-14-2009, 08:49 PM

A little clarification...this is working except when I click the "onesies" link, then click one of the other links. The if statement should read that the variable "current_link" has a value of "onesies", then run the "else" portion of the if/else statement. But it runs the "if" portion. So something must be wrong with the setting of my variable, and reading it in the if/else statement.

MikeTheVike · 09-14-2009, 08:57 PM

Using some alert statements, it looks like my variables are being written and changed correctly when the links are pressed, so the problem must have something to do with the if/else statement

Edit: I've been doing some more debugging and it is running the first if statement even if it is not true, rather than the else statement. Anyone know why?

CkretAjint · 09-14-2009, 09:32 PM

Are you using any other js add ones for this? I was on my site and 1 add on (prototype.js) was canceling out all of my jQuery scripts.

Sorry I can't be of much more help...

Two-Toe Tom · 09-14-2009, 11:51 PM

it's because you're just assigning "bases1" to $current_link. to test for equality you have to use ==.

tZ · 09-15-2009, 12:48 AM

HTML Code:

    $(function() {
    
    	/*
    	* To be accessible to all functions
    	* current link must be defined here.
    	*/
    	var current_link = '';
    
        $('a.click_rotors').click(function() {
             if (current_link == "bases1") {
             $('#bases1').fadeOut(function () {
                 $('#rotors1').fadeIn();
             });
             } else {
             $('#onesies').fadeOut(function () {
                 $('#rotors1').fadeIn();
             });
             };               
             current_link = "rotors1";
        });

        $('a.click_bases1').click(function() {
             if (current_link == "rotors1") {
             $('#rotors1').fadeOut(function () {
                 $('#bases1').fadeIn();
             });
             } else {
             $('#onesies').fadeOut(function () {
                 $('#bases1').fadeIn();
             });
             };             
             current_link = "bases1";
        });

        $('a.click_onesies').click(function() {
             if (current_link == "rotors1") {
             $('#rotors1').fadeOut(function () {
                 $('#onesies').fadeIn();
             });
             } else {
             $('#bases1').fadeOut(function () {
                 $('#onesies').fadeIn();
             });  
             };             
             current_link = "onesies";
        });
    });

tZ · 09-15-2009, 01:06 AM

You can try this out for a simplified version. Although, there is probably a syntax error somewhere.

HTML Code:

$(function() {
	
	var funcOnClick = 
	(function() {
	
		var objCurrent = null;
	
		return function(objThis) {
			if(!objCurrent) {
				objThis.fadeIn(function() {
					objCurrent = objThis;
				});
			} else if(objCurrent !== objThis) {
				objCurrent.fadeOut(function() {
					objThis.fadeIn(function() {
						objCurrent = objThis;
					});
				});
			}
		}
	
	})();
	
	var objRotors = $('a.click_rotors');
	var objBases1 = $('a.click_bases1');
	var objOnsies = $('a.click_onesies');
	
	objRotors.click(function() {
		funcOnClick(objRotors);
	});
	
	objBases1.click(function() {
		funcOnClick(objBases1);
	});
	
	objOnsies.click(function() {
		funcOnClick(objOnsies);
	});

});

Tracking state like this has to do with closures not JQuery. The short verison is that a function in JavaScript has access to all variables defined outside of it. However, it does not have direct access to variables within nested functions - only things above. This makes it possible to bind a variable to a function explicitly then change it to track state. That is essentially what is happening with currentLink in the above code. The variable currentLink is bound to the returned function. making it possible to change it from within the scope of that returned function. Yet, keep it entirely out of the scope of everything besides that function. maybe some of that made some sense…

It took a me a long time to understand closures and binding. However, once you do its a very powerful concept.

MikeTheVike · 09-15-2009, 12:17 PM

Originally posted by Two-Toe Tom View Post

it's because you're just assigning "bases1" to $current_link. to test for equality you have to use ==.

Thanks, its funny because I know that is how it is in Actionscript 3.0, but everything I found online never said anything about using two equal signs. It worked, thanks!

MikeTheVike · 09-15-2009, 12:21 PM

Originally posted by tZ View Post

You can try this out for a simplified version. Although, there is probably a syntax error somewhere.

HTML Code:

$(function() {
	
	var funcOnClick = 
	(function() {
	
		var objCurrent = null;
	
		return function(objThis) {
			if(!objCurrent) {
				objThis.fadeIn(function() {
					objCurrent = objThis;
				});
			} else if(objCurrent !== objThis) {
				objCurrent.fadeOut(function() {
					objThis.fadeIn(function() {
						objCurrent = objThis;
					});
				});
			}
		}
	
	})();
	
	var objRotors = $('a.click_rotors');
	var objBases1 = $('a.click_bases1');
	var objOnsies = $('a.click_onesies');
	
	objRotors.click(function() {
		funcOnClick(objRotors);
	});
	
	objBases1.click(function() {
		funcOnClick(objBases1);
	});
	
	objOnsies.click(function() {
		funcOnClick(objOnsies);
	});

});

Tracking state like this has to do with closures not JQuery. The short verison is that a function in JavaScript has access to all variables defined outside of it. However, it does not have direct access to variables within nested functions - only things above. This makes it possible to bind a variable to a function explicitly then change it to track state. That is essentially what is happening with currentLink in the above code. The variable currentLink is bound to the returned function. making it possible to change it from within the scope of that returned function. Yet, keep it entirely out of the scope of everything besides that function. maybe some of that made some sense…

It took a me a long time to understand closures and binding. However, once you do its a very powerful concept.

Thanks tZ, I thought there had to have been a simpler way. I'll give it a try.

Need some with with JQuery and an if/else if statement...

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