[Javascript]How to write One-Time EventListener


In modern major browsers, you don’t need removeEventListener or flags to execute an event only once in JavaScript.
There’s a fantastic option available, so let’s take a closer look.





addEventListener Once

Just by adding {once: true} to the third argument for addEventListener, it will execute the event only once. Wonderful!

window.addEventListener('scroll', () => {
    
}, {once: true})





In the case of jQuery

In the case of jQuery, the “one” method is available.

$(window).one('scroll', () => {
    
})





Browser support for {once: true}

It appears that {once: true} is already supported in major browsers.

Reference:“once” event listener option” | Can I use…





If IE support is required

If IE support is necessary, we have no choice but to use removeEventListener.
It seems to be supported in IE9 and above.

Reference:“removeEventListener” | Can I use…

window.addEventListener('scroll', hoge = () => {
    // Perform some operation before executing removeEventListener.
    this.removeEventListener('scroll', hoge)
})






That is all, it was about how to write One-Time EventListener.

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