Javascript: void (0) & refresh page

1 <a href = "#" onclick = "javascript: add ();">
Because the href = "#" element will automatically jump the page to the top, so the page will be beating and there is no partial refresh experience.
2. Remove #. The remaining href = "" will not work either. This will refresh the page after loading.
3, <a href = "javascript: void (0)">.

The meaning of void (0) in javascript:
In JavaScript, void is an operator that specifies to calculate an expression but does not return a value.
The format of the void operator is as follows:
1. javascript: void (expression)
2. javascript: void expression
Expression is a standard JavaScript expression to be calculated. Parentheses outside the expression are optional, but it is a good habit to write. You can use the void operator to specify a hyperlink. The expression is calculated, but no content is loaded in the current document. The above Code creates a hyperlink, and nothing will happen after the user clicks it. When a user clicks a link, void (0) is calculated as 0, but it has no effect on JavaScript.
<A href = "javascript: void (0)"> click here. </a>
That is to say, if you want to perform some processing, but do not refresh the page as a whole, you can use void (0). However, when you need to refresh the page, you have to be careful.

<A href = "javascript: void (document. Form. Submit ()"> This statement performs a submit operation. Under what circumstances will void (0) be used more often, without refreshing the new version? Of course it is Ajax. If you look at Ajax web pages, you will usually see a lot of void (0 ), so before using void (0), you 'd better think about whether the page needs to be refreshed as a whole.

Another method: onclick = "...; return false;" href = "#"