JSFiddle - React, Tailwind, and code Playground

HTML

<div id='x'></div>

JavaScript

var html = '<div style="background-image:url(\'img.png\');"></div> \
<div style=\'background-image:url("img.png");\'></div> \
<div style=\'background-image:url(img.png);\'></div> \
<div style=\'background-image:url(../../img.png);\'></div> \
<div style=\'background:  #ffffff   url( "img.png" )   no-repeat right top;\'></div>';

var matches = html.match(/url\([^(]+\)/ig);
for(var i = 0; i < matches.length; i++) {
    var url = matches[i].replace(/(^url\s*\(\s*['"]?)|(['"]?\s*\)$)/ig, '');
    $('#x').append(url + '<br />');
}