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Why use void(0) in JavaScript?



The void operator evaluates the given expression and then returns undefined. If you have pass 0 as the unary expression operand to the void operator, JavaScript coerces 0 to "false" and returns, but void doesn't care and simply returns undefined, which means "do nothing" . Put them together and you have composed a way to programmatically "do nothing" when a link is clicked. JavaScript Void(0) is often used when, inserting an expression into a web page may produce an unwanted side-effect.

You may occasionally encounter an HTML document that uses href="JavaScript:Void(0);" within an < a > element.

A common usage of JavaScript:Void(0) is with hyperlinks. Usually, when the user clicks a link on a page a new page loads, but this is not always the desired course of action. For example, when the user clicks a link on a page, you might want to update the value of a field in a form or the value of a variable. To prevent a page from reloading when a link is clicked, the void(0) function is used.

example

output

run this source code Try it Yourself
Click me!

When you click on the above link. Even though the code within it specifies to display a message in an alert box (and this action does take place), the page will reload automatically.

To prevent the page reloading, we can use JavaScript:void(0); within the anchor link.

output

run this source code Try it Yourself
Click me!

When you run the above example, you can see a message is displayed in an alert box as intended and void(0) prevents the page from reloading . So the void operator can be useful when you need to call another function that may have otherwise resulted in an unwanted page refresh.










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