JSFiddle - React, Tailwind, and code Playground

by GRMule

HTML

<input class="selectme quantity" value="4.5">
<input class="selectme quantity" value="1">
<input class="selectme quantity" value="5">

JavaScript

(function($){
 	$.fn.extend({ 
 		addElementValues: function() {
    		var sum = 0;
            this.each(function() {
                sum += (typeof this.value != 'undefined' ? parseInt(this.value, 10) : 0);
    		});
            return sum;
    	}
	});
})(jQuery);

console.log($('.selectme').addElementValues());