Jquery - Simple Array, pushing item in if its not there already, removing item if it is there

Question

I'm building a simple filtering system, I simply want to add a string to an array and remove it if its already there on click of a link. I'll try to explain the best I can..

$(document).ready(function(){     //so I start with an empty array     var filters [];     //when a link is clicked I want to add it to the array..     $('li a', context).click(function(e){         //so I get the value held in the data-event attribute of the clicked item example: "john"         newFilter = $(this).attr('data-event');         //this is where I get stuck, I want to test to see if the string I now have         //in 'newFilter' is in the array already or not.. if it is in the array I         //want to remove it, but if it doesnt exist in the array i want to add it..         if(jQuery.inArray(newFilter, filters){             //add to array         } else {            //remove from array         };     e.preventDefault();     }); }); 

Answer 1

$.inArray() returns the index of the item if it is found, and -1 otherwise (just like indexOf() does, when supported). Therefore, you can write something like:

var found = jQuery.inArray(newFilter, filters); if (found >= 0) {     // Element was found, remove it.     filters.splice(found, 1); } else {     // Element was not found, add it.     filters.push(newFilter); } 

Answer 2

I could be wrong, but I believe this is as simple as using basic javascript: _{[.push, .splice]}

if($.inArray(newFilter, filters)<0) {     //add to array     filters.push(newFilter); // <- basic JS see Array.push }  else {     //remove from array     filters.splice($.inArray(newFilter, filters),1); // <- basic JS see Array.splice }; 

Of course if you really want to simplify it you could remove some lines and reduce it to inline coding.

0 > $.inArray(newFilter,filters) ? filters.push(newFilter) : filters.splice($.inArray(newFilter,filters),1); 

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For ABSOLUTE pure JS:

var i; (i=filters.indexOf(newFilter))<0?filters.push(newFilter):filters.splice(i,1); 

Broken down:

var i;  //  Basic variable to be used if index of item exist //  The following is simply an opening to an inline if statement. //  It's wrapped in () because we want `i` to equal the index of the item, if found, not what's to follow the `?`. //  So this says "If i = an index value less than 0". (i=filters.indexOf(newFilter)) < 0 ?     //  If it was not found, the index will be -1, thus push new item onto array     filters.push(newFilter) :          //  If found, i will be the index of the item found, so we can now use it to simply splice that item from the array.         filters.splice(i,1);