📅  最后修改于: 2022-03-11 15:03:01.258000             🧑  作者: Mango
var myEle = document.getElementById("myElement");
if(myEle){
var myEleValue= myEle.value;
}
//the return of getElementById is null if an element is not actually
//present inside the dom, so your if statement will fail, because null
//is considered a false value