What does this javascript code do? [closed]

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Closed 9 years ago.

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this code takes a url as input, but I'm not sure what it does or what's the benefit of doing this

var hashPos = url.lastIndexOf ( '#' );
return url.substring( hashPos + 1 );

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It fetches the hash value off a URL:

So, if the URL is this: http://something.com/foo#xyz, it gets the xyz

If there is no hash mark in the URL, this code returns the entire URL (which may not be the desired outcome).

This is probably a safer variation that returns an empty string, when there is no hash value:

var hashPos = url.lastIndexOf ( '#' );
if (hashPos != -1) {
    return url.substring( hashPos + 1 );
} else {
    return("");
}

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It returns whatever is after the # in the url.

Details:

var hashPos = url.lastIndexOf ( '#' ); // Gets the position of the last # found in the string.
return url.substring( hashPos + 1 ); // Gets a piece of the string starting at the given position (hashpos + 1).

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It gets everything in the URL after the hash (#) mark.

var url = "http://www.mysite.com/test#somesection";

var hashPos = url.lastIndexOf ( '#' );  
return url.substring( hashPos + 1 );  //returns "somesection"

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Returns the part of the string from just after the last # character to the end. i.e a location in that page.

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var hashPos = url.lastIndexOf ( '#' ); 

This grabs the location of the hash char (#) in the URL string.

return url.substring( hashPos + 1 ); 

This then returns everything after the location of the hash in the url string.

A result would be the hash tag. This is used alot for AJAX applications, where you would like to keep a page state, and be able to link to that state without actually linking to a seperate page.

An example would be:

var recent_hash = "";                       
setInterval(poll_hash, 100); // Initialize our hash polling interval for ajax urls

function poll_hash() {
 if (url.substring( hashPos + 1 ) == recent_hash) { return; }   // No change
 recent_hash = url.substring( hashPos + 1 );
 process_hash(recent_hash); 
}

function process_hash(hash_id)
{
 var ajax_url = '/ajax/link_hash/' + hash_id;
 $('#some_div').load(ajax_url)
}