I'm setting up a chrome extension and have the settings menu built, the CSS and HTML work fine. I'm using this button on Codepen and it says my code has no errors 
How do I define the function? I have now downloaded jquery to the folder and called it using script as seen here
using the CDN didn't work because of some security restrictions for developing an extension.
$('button.cooldown').click(function(){
var btn = $(this);
btn.prop('disabled', true);
setTimeout(function(){
btn.prop('disabled', false);
},15000);
});body {
background-image: linear-gradient( 72.5deg, rgba(0,175,255,1) 27.9%, rgba(0,224,254,1) 84.2% );
width: 250px;
height: 400px;
}
#header {
padding-top: 2px;
padding-bottom: 2px;
text-align: center;
background-color: #393e46;
color: white;
font-size: 15px;
border-radius: 10px;
}
.button {
background-color: rgb(80, 220, 100);
border: none;
color: white;
padding: 15px 32px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
cursor: pointer;
border-radius: 50px;
margin: 5px;
}
.button:hover {
background-color: #393e46;
border: none;
color: white;
padding: 15px 32px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
cursor: pointer;
border-radius: 50px;
margin: 5px;
}
.button_cancel {
background-color: #f44444;
border: none;
color: white;
padding: 15px 32px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
cursor: pointer;
border-radius: 50px;
margin: 5px;
}
.button_cancel:hover {
background-color: #393e46;
border: none;
color: white;
padding: 15px 32px;
text-align: center;
text-decoration: none;
display: inline-block;
font-size: 16px;
cursor: pointer;
border-radius: 50px;
margin: 5px;
}
/* The container */
.container {
display: block;
position: relative;
padding-left: 10px;
margin-bottom: 12px;
cursor: pointer;
font-size: 22px;
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
/* Hide the browser's default checkbox */
.container input {
position: absolute;
opacity: 0;
cursor: pointer;
height: 0;
width: 0;
font-size: 18px;
}
/* Create a custom checkbox */
.checkmark {
position: absolute;
top: 0;
left: 0;
height: 25px;
width: 25px;
background-color: #eee;
}
/* On mouse-over, add a grey background color */
.container:hover input ~ .checkmark {
background-color: #ccc;
}
/* When the checkbox is checked, add a blue background */
.container input:checked ~ .checkmark {
background-color: #2196F3;
}
/* Create the checkmark/indicator (hidden when not checked) */
.checkmark:after {
content: "";
position: absolute;
display: none;
}
/* Show the checkmark when checked */
.container input:checked ~ .checkmark:after {
display: block;
}
/* Style the checkmark/indicator */
.container .checkmark:after {
left: 9px;
top: 5px;
width: 5px;
height: 10px;
border: solid white;
border-width: 0 3px 3px 0;
-webkit-transform: rotate(45deg);
-ms-transform: rotate(45deg);
transform: rotate(45deg);
}
input[type=text], select {
width: 100%;
padding: 12px 20px;
margin: 8px 0;
display: inline-block;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
input[type=file], select {
padding-left: 15%;
}
.form-item {
padding-top: 2px;
padding-bottom: 2px;
text-align: center;
}
.wallpaper-title {
display: block;
padding-bottom: 3px;
font-size: 11px;
}
button.cooldown {
background: #336699;
min-height: 48px;
min-width: 144px;
position: relative;
margin: 5px;
border-radius: 5px;
border: 0;
color: #fff;
padding: 0 15px;
font-size: 16px;
outline: none;
overflow: hidden;
cursor: pointer;
}
button.cooldown:active, button.cooldown:focus {
outline: none;
}
button.cooldown:disabled {
background: #264d73;
color: #d9d9d9;
cursor: default;
box-shadow: inset 3px 3px 10px 0px rgba(0, 0, 0, 0.2);
}
button.cooldown:disabled:after {
content: '';
position: absolute;
bottom: 0;
width: 100%;
left: 0;
height: 5px;
background: #1a334d;
animation: cooldown 15s linear;
}
@keyframes cooldown {
0% {
width: 100%;
}
100% {
width: 0;
}
}
/* layout stuff */
section {
text-align: center;
margin-top: 100px;
color: #333;
}
p {
font-size: 12px;
}<html>
<head>
<title>Home+</title>
<link rel="stylesheet" type="text/css" href="popup.css">
<script src="popup.js"></script>
<div id="header">
<h2>Home+</h2>
<h6>Settings</h6>
</div>
</head>
<body>
<!-- The settings pane, expand at will -->
<div class="tab-pane" id="settings">
<form class="settings">
<div class="form-item">
<label for="zip">Zip Code: </label>
<div class="form-item">
<input id="zip" name="zip" type="text" pattern="[0-9]*">
</div>
</div>
<div class="form-item">
<label class="container">Show Weather
<input type="checkbox" checked="checked">
<span class="checkmark"></span>
</label>
</div>
<div class="form-item">
<button class="cooldown">Refresh Weather</button>
</div>
<div class="form-item">
<label for="hompagebg" class="wallpaper-title">Upload Wallpaper</label>
<center>
<input type="file" id="hompage-background" name="hompagebg" accept="image/png, image/jpeg" size="20">
</center>
</div>
<div class="form-item">
<button type="button" class="button">Save</button>
<button type="button" class="button_cancel">Cancel</button>
</div>
</form>
</div>
</div>
</body>
</html>
