JS jQuery - check if value is in array
You are comparing a jQuery object (jQuery('input:first')) to strings (the elements of the array).
Change the code in order to compare the input's value (wich is a string) to the array elements:
if (jQuery.inArray(jQuery("input:first").val(), ar) != -1)The inArray method returns -1 if the element wasn't found in the array, so as your bonus answer to how to determine if an element is not in an array, use this :
if(jQuery.inArray(el,arr) == -1){ // the element is not in the array};
As to your bonus question, try if (jQuery.inArray(jQuery("input:first").val(), ar) < 0)
Alternate solution of the values check
//Duplicate Title Entry $.each(ar , function (i, val) { if ( jQuery("input:first").val()== val) alert('VALUE FOUND'+Valuecheck); });