here for green background
    </a>
    

**Note:** ` javascript: ` pseudo protocol is discouraged over other
alternatives, such as unobtrusive event handlers.

###  Non-leaking Arrow Functions

Arrow functions introduce a short-hand braceless syntax that returns an
expression. This can cause unintended side effects if the expression is a
function call where the returned value changes from ` undefined ` to some
other value.

For example, if ` doSomething() ` returns ` false ` in the code below, the
checkbox will no longer be marked as checked or unchecked when the checkbox is
clicked (returning ` false ` from the handler disables the default action).

js

    
    
    checkbox.onclick = () => doSomething();
    

This is unlikely to be desired behaviour! To be safe, when the return value of
a function is not intended to be used, it can be passed to the ` void `
operator to ensure that (for example) changing APIs do not cause arrow
functions' behaviors to change.

js

    
    
    checkbox.onclick = () => void doSomething();
    

##  Specifications

Specification  
---  
[ ECMAScript Language Specification  
#  sec-void-operator  ](https://tc39.es/ecma262/multipage/ecmascript-language-
expressions.html#sec-void-operator)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` undefined ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/undefined)

##  Help improve MDN

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