JS jQuery - check if value is in array

Question

I am more of a PHP person, not JS - and I think my problem is more a syntax problem ..

I have a small jQuery to \"validate\" and check input value .

It works ok

Answer 1

The Array.prototype property represents the prototype for the Array constructor and allows you to add new properties and methods to all Array objects. we can create a prototype for this purpose

Array.prototype.has_element = function(element) {
    return $.inArray( element, this) !== -1;
};

And then use it like this

var numbers= [1, 2, 3, 4];
numbers.has_element(3) => true
numbers.has_element(10) => false

See the Demo below

Array.prototype.has_element = function(element) {
  return $.inArray(element, this) !== -1;
};



var numbers = [1, 2, 3, 4];
console.log(numbers.has_element(3));
console.log(numbers.has_element(10));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Answer 2

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
};

Answer 3

As to your bonus question, try if (jQuery.inArray(jQuery("input:first").val(), ar) < 0)

Answer 4

Alternate solution of the values check

//Duplicate Title Entry 
    $.each(ar , function (i, val) {
        if ( jQuery("input:first").val()== val) alert('VALUE FOUND'+Valuecheck);
  });