2 回答

TA貢獻(xiàn)1803條經(jīng)驗(yàn) 獲得超6個(gè)贊
嘗試這種方式..
const btnMenu=document.querySelector('#btnMenu');
btnMenu.addEventListener('click', function(){
console.log('open menu');
if(btnMenu.classList.contains('open')){
btnMenu.classList.remove('open')
}
else{
btnMenu.classList.add('open')
}
});

TA貢獻(xiàn)1719條經(jīng)驗(yàn) 獲得超6個(gè)贊
因?yàn)閎tnMenu被設(shè)置為addEventListener- 這不是對(duì)按鈕的引用的結(jié)果。該方法返回undefined!
在事件偵聽(tīng)器函數(shù)中將this引用元素:
document.querySelector('#btnMenu')
.addEventListener('click', function() {
console.log('open menu');
if (this.classList.contains('open')) {
this.classList.remove('open')
} else {
this.classList.add('open')
}
});
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