How Do I get a page's URL using JSOM - sharepoint

Question

I am using SharePoint 2013 workflow.
I am in the Initiation form when my my users clock the Start button to start the workflow.
I am using JSOM to start the workflow but since I am on the Initiation form, I don't know the URL of the page. I do know the list (pages) and the the list id (2).
Can someone help me retrieve the list id's url using JSOM?
Thanks
Tom

Answer 1

How to get Page Url in Initiation Form page:
var listId = getParameterByName('List');
var itemId = getParameterByName('ID');
var ctx = new SP.ClientContext.get_current();
var web = ctx.get_web();
var list = web.get_lists().getById(listId);
var listItem = list.getItemById(itemId);
ctx.load(listItem);
ctx.executeQueryAsync(
function () {
var itemUrl = listItem.get_item('FileRef');
console.log(itemUrl);
},
function (sender, args) {
console.log(args.get_message());
}
);
,where
function getParameterByName(name) {
name = name.replace(/[\[]/, "\\[").replace(/[\]]/, "\\]");
var regex = new RegExp("[\\?&]" + name + "=([^&#]*)"),
results = regex.exec(location.search);
return results == null ? "" : decodeURIComponent(results[1].replace(/\+/g, " "));
}
is intended for retrieving parameter from query string
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