JSFiddle - React, Tailwind, and code Playground

HTML

<div><span name="user[1][name]">Bob</span></div>
<div>Double Escape: <span id="result1"></span></div>
<div>Single Escape: <span id="result2"></span></div>
<div>Double Escape w/ Key: <span id="result3"></span></div>
<div>Single Escape w/ Key: <span id="result4"></span></div>
<div>Double Escape w/ Regex (<span id="regex1"></span>): <span id="result5"></span></div>
<div>Single Escape w/ Regex (<span id="regex2"></span>): <span id="result6"></span></div>

JavaScript

$('#result1').html($('span[name=user\\[1\\]\\[name\\]]').html());
$('#result2').html($('span[name=user\[1\]\[name\]]').html());

var key_double = 'user\\[1\\]\\[name\\]';
var key_single = 'user\[1\]\[name\]';
$('#result3').html($('span[name=' + key_double + ']').html());
$('#result4').html($('span[name=' + key_single + ']').html());

var key = 'user[1][name]';
var key_regex_double = key.replace(/([\[\]])/g, "\\\\$1");
var key_regex_single = key.replace(/([\[\]])/g, "\\$1");
$('#result5').html($('span[name=' + key_regex_double + ']').html());
$('#regex1').html(key_regex_double);
$('#result6').html($('span[name=' + key_regex_single + ']').html());    
$('#regex2').html(key_regex_single);