The regular expression seems to work in Javascript to some extent without any modification - see regex101 demo. Just remember to escape all backslashes (\\ in place of \) and single quotes ('' instead of ') if defining it in a single-quoted Javascript string:
var jsRegex = new RegExp('^((https?|ftp):\\/\\/)?(((([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-fA-F]{2})|[!\\$&''\\(\\)\\*\\+,;=]|:)*@)?(((\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5]))|([a-zA-Z][\\-a-zA-Z0-9]*)|((([a-zA-Z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(([a-zA-Z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])*([a-zA-Z]|\\d|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])))\\.)+(([a-zA-Z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(([a-zA-Z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])*([a-zA-Z]|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])))\\.?)(:\\d*)?)(\\/((([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-fA-F]{2})|[!\\$&''\\(\\)\\*\\+,;=]|:|@)+(\\/(([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-fA-F]{2})|[!\\$&''\\(\\)\\*\\+,;=]|:|@)*)*)?)?(\\?((([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-fA-F]{2})|[!\\$&''\\(\\)\\*\\+,;=]|:|@)|[\\uE000-\\uF8FF]|\\/|\\?)*)?(\\#((([a-zA-Z]|\\d|-|\\.|_|~|[\\u00A0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|(%[\\da-fA-F]{2})|[!\\$&''\\(\\)\\*\\+,;=]|:|@)|\\/|\\?)*)?$', 'i');
// ...or...
var jsRegex = /^((https?|ftp):\/\/)?(((([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-fA-F]{2})|[!\$&'\(\)\*\+,;=]|:)*@)?(((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]))|([a-zA-Z][\-a-zA-Z0-9]*)|((([a-zA-Z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-zA-Z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-zA-Z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-zA-Z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-zA-Z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-zA-Z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?)(:\d*)?)(\/((([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-fA-F]{2})|[!\$&'\(\)\*\+,;=]|:|@)+(\/(([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-fA-F]{2})|[!\$&'\(\)\*\+,;=]|:|@)*)*)?)?(\?((([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-fA-F]{2})|[!\$&'\(\)\*\+,;=]|:|@)|[\uE000-\uF8FF]|\/|\?)*)?(\#((([a-zA-Z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-fA-F]{2})|[!\$&'\(\)\*\+,;=]|:|@)|\/|\?)*)?$/i;
Note: The i modifier is assuming this needs case-insensitive matching.
(If the above isn't sufficient, please be more specific about what isn't working.)
Is there any tool or any easy way to convert this regex to work in JS?
The only generic tool I'm aware of that supposedly converts between regex flavors is RegexBuddy - but it is paid for software (€29.95) - although if for any reason it didn't work you could get a refund.