What does JavaScript void 0 mean

This code is often visible in JavaScript scripts:





〈a href= "Javascript:changenum (); void (0);" 〉here〈/a〉





but what does void (0) mean here? What's the effect?





JavaScript Void is an operator that specifies that you want to evaluate an expression but not return a value.





void operator Usage format is as follows:





1. Javascript:void (e?xpression)





2. Javascript:void e?xpression





E?xpression is an expression of the JavaScript standard to compute. The parentheses outside the expression are optional, but writing is a good habit. You can use the void operator to specify a hyperlink. The expression is evaluated but does not mount any capacity at the current document.





The following code creates a hyperlink that will not happen when the user clicks on it. When the user clicks on the link, void (0) evaluates to 0, but there is no effect on JavaScript.





<a href= "javascript:void (0)" > Click here Nothing will happen </A>





The following code creates a hyperlink that submits the form when the user clicks it.





<a href= "Javascript:void (Document.form.submit ())" > Click here to submit the form </A>





When using JavaScript, we usually go through something like: <a href= http://www.webyi.com/wschool/program/javascript/20091231/"# onclick=" JavaScript: Method > Submit </a> by using a pseudo link to invoke the JavaScript method. One problem with this approach is that although clicking the link does not jump the page, the scroll bar rolls up, and the solution is to return a false.





looks like this:





<a href= http://www.webyi.com/wschool/program/javascript/20091231/"#" onclick= "javascript: method; return false;" > Submit </a>





<a href= http://www.webyi.com/wschool/program/javascript/20091231/"javascript:void (0)" onclick= "javascript : method; return false; > Submit </a>





<a href= http://www.webyi.com/wschool/program/javascript/20091231/"#this" onclick= "javascript: Method" >xx </a>





# contains a location information the default anchor point is #top, which is the top of the page, and javascript:void (0) only represents a dead link. This is why sometimes the page is very long browsing links obviously is # but it beats to the top of the page, and javascript:void (0) is not so it is best to invoke a script with void (0).





　　So we do not refresh the page with void (0) More, is generally Ajax, look at Ajax Web pages, the general will see a lot of void (0), so in the use of void (0), it is best to think about whether the page needs to be a whole refresh.