How to write ternary operator condition in jQuery

Question

In this fiddle http   jsfiddle net mjmitche 6nar4 3   if you drag  for example  the little blue box into the yellow box  then the big black box will turn pink  All of the 4 boxes along the left can be dragged into the boxes inside the black box    At the end of the fiddle  you see the code that changes the black box to pink   However  I want to make that a ternary operator  so that if the box is black  then it turns pink  but if it s been turned pink  then I want it to go back to black    I know the ternary is like this  x   y  z   So I tried this  even though I knew it wasn t probably right      blackbox   css   background   pink                blackbox   css   background   black             blackbox   css   background   pink        I think the first line before the question mark is causing the problem  so how to create the if statement

User · Answer

Ternary operator works because the first part of it returns a Boolean value  In your case  jQuery s css method returns the jQuery object  thus not valid for ternary operation

User · Answer

I would go with such code   var oBox       blackbox    var curClass   oBox attr  class    var newClass    curClass     bg black      bg pink     bg black   oBox removeClass   addClass newClass     To have it working  you first have to change your CSS and remove the background from the  blackbox declaration  add those two classes    bg black   background-color   000     bg pink   background-color  pink      And assign the class bg black to the blackbox element initially   Updated jsFiddle  http   jsfiddle net 6nar4 17   In my opinion it s more readable than the other answers but it s up to you to choose of course

User · Answer

I d do  added caching    var bbx       blackbox     bbx css  background-color        rgb 255  192  203     bbx css  background   black     bbx css  background   pink     wroking fiddle  new AGAIN   http   jsfiddle net 6nar4 37   I had to change the first operator as css   returns the rgb value of the color

User · Answer

I think Dan and Nicola have suitable corrected code  however you may not be clear on why the original code didn t work   What has been called here a  ternary operator  is called a conditional operator in ECMA-262 section 11 12  It has the form   LogicalORExpression   AssignmentExpression   AssignmentExpression   The LogicalORExpression is evaluated and the returned value converted to Boolean  just like an expression in an if condition   If it evaluates to true  then the first AssignmentExpression is evaluated and the returned value returned  otherwise the second is evaluated and returned   The error in the original code is the extra semi-colons that change the attempted conditional operator into a series of statements with syntax errors

User · Answer

Here is a working example in side a function     x000D   x000D  function setCurrency    x000D     var returnCurrent  x000D         RequestCurrencyType   is   checked       true   returnCurrent    Dollar   returnCurrent    Euro   x000D      x000D     return returnCurrent  x000D    x000D   x000D   x000D    In your case  Change the selector and the return values   x000D   x000D      blackbox   css  background-color        pink    return  black    return  pink   x000D   x000D   x000D    lastly  to know what is the value used by the browser run the following in the console    x000D   x000D      blackbox   css  background-color   x000D   x000D   x000D    and use the  rgb xxx xxx xxx   value instead of the Hex for the color selection

User · Answer

Also  the ternary operator expects expressions  not statements  Do not use semicolons  only at the end of the ternary op       blackbox   css   background            blackbox   css  background        pink     black     pink

User · Answer

As others have correctly pointed out  the first part of the ternary needs to return true or false and in your question the return value is a jQuery object   The problem that you may have in the comparison is that the web color will be converted to RGB so you have to text for that in the ternary condition   So with the CSS    blackbox       background pink      width 10px      height 10px      The following jQuery will flip the colour   var b       blackbox    b css  background    b css  backgroundColor        rgb 255  192  203      black     pink       Demo

User · Answer

The Ternary operator is just written as a boolean expression followed by a questionmark and then two further expressions separated by a colon   The first thing that I can see that you have got wrong is that your first expression isn t returning a boolean or anything sensible that could be converted to a boolean  Your first expression is always going to return a jQuery object that has no sensible interpretation as a boolean and what it does convert to is probably an unchanging interpretation  You are always best off returning something that has a well known boolean interpretation  if nothign else for the sake of readability   The second thing is that you are putting a semicolon after each of your expressions which is wrong  In effect this is saying  end of construct  and so is breaking your ternary operator   In this situation though you probably can do this a more easy way  If you use classes and the toggleClass method then you can easily get it to switch a class on and off and then you can put your styles in that class definition  Kudos to  yoavmatchulsky for suggesting use of classes up there in comments    A fiddle of this is found here  http   jsfiddle net chrisvenus wSMnV   based on the original

User · Answer

From what it looks like you are trying to do  toggle might better solve your problem    EDIT  Sorry  toggle is just visibility  I don t think it will help your bg color toggling   But here you go   var box       blackbox    box css  background       pink    box css   background   black      box css   background   pink

[javascript] How to write ternary operator condition in jQuery?

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