我正在尝试检查以下情况,
var param= document.getElementById("txtbox").value;
if(param!== null || param.length!==0 || param !=="" || param!==undefined)
{//do something}
但是即使param为null,它也会进入if块。有人对此有想法吗?
这怎么办:
var param= document.getElementById("txtbox");
if(!param && !param.value)
{
您可以null
检查元素,
var param= document.getElementById("txtbox");
if(param!== null)
{
//Your business logic
}
var htmlElement = document.getElementById("txtbox")
if (!!htmlElement && !!htmlElement.value) {
console.log('element exists and not null!')
}
<div id="txtbox" value="some value">
something
</div>