更改输入值的简单 jQuery 调用继续返回 TypeError $(...) 为 null

Question

My hair is falling out while I'm trying to figure out why jQuery keeps throwing a TypeError for what I think is a valid call to replace an input value in the HTML.

The line below is being called in one of my functions to change all of the input values for those with the name "form_key."

$('input[name="form_key"]').val("ItWorks!");

(resides in http://vt2.net/js/warp/warp.js )

There are multiple pages that have this hidden input name and some pages have it more than once, and I'm trying to change the value for all on the page.

The page below only has one but Firebug keeps showing a TypeError no matter how many ways I try to replace the value. http://vt2.net/my-test-product.html

It's probably something really simple and stupid but I keep missing it! Any ideas?

Answer 1

You already use

http://vt2.net/js/lib/jquery/noconflict.js

where define

// Avoid PrototypeJS conflicts, assign jQuery to $j instead of $
var $j = jQuery.noConflict();

So for all operation by jQuery, you need use $j instead just $

And your $ now from prototype.js

function $(element) {
  if (arguments.length > 1) {
    for (var i = 0, elements = [], length = arguments.length; i < length; i++)
      elements.push($(arguments[i]));
    return elements;
  }
  if (Object.isString(element))
    element = document.getElementById(element);
  return Element.extend(element);
}

Answer 2

Kevin B is right $ is not jQuery on http://vt2.net/my-test-product.html .

Use

jQuery('input[name="form_key"]').val("ItWorks!");

Or

jQuery.noConflict()