What does “[removed]void(0)” mean?

Question

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I\'ve seen such hrefs many times, but I don\'t know what exactly

Answer 1

A link must have an href target to be specified to enable it to be a usable display object.

Most browsers will not parse advanced JavaScript in the href of an element, for example:

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Because the href tag in most browsers does not allow whitespace or will convert whitespace to %20 (the HEX code for space), the JavaScript interpreter will run into multiple errors.

So if you want to use an element's href to execute inline JavaScript, you must specify a valid value for href first that isn't too complex (doesn't contain whitespace), and then provide the JavaScript in an event attribute tag like onClick, onMouseOver, onMouseOut, etc.

The typical answer is to do something like this:

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This works fine but it makes the page scroll to the top because the # in the href tells the browser to do this.

Placing a # in the element's href specifies the root anchor, which is by default the top of the page, but you can specify a different location by specifying the name attribute inside an element.

You can then change your element's href to jump to middleOfPage and execute the JavaScript in the onClick event:

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There will be many times where you do not want that link jumping around, so you can do two things:

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Now it will go nowhere when clicked, but it could cause the page to re-centre itself from its current viewport.

The best way to use in-line javascript using an element's href, but without having to do any of the above is JavaScript:void(0);:

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This tells the browser no to go anywhere, but instead execute the JavaScript:void(0); function in the href because it contains no whitespace, and will not be parsed as a URL. It will instead be run by the compiler.

void is a keyword which, when supplied with a parameter of 0 returns undefined, which does not use any more resources to handle a return value that would occur without specifying the 0 (it is more memory-management/performance friendly).

The next thing that happens is the onClick gets executed. The page does not move, nothing happens display-wise.