I would like to ask, because I had this understanding when I was learning before that the declaration of var is a global variable outside function, which is generally written outside it for easy calling.
but encountered this example to get the declaration of ID needs to be written in the function, written outside the function, then the code cannot be executed.
var inp1=document.getElementById("inp1").value,
inp2=document.getElementById("inp2").value,
btn=document.getElementById("btn");I really don"t know why.
<body>
<input type="text" id="inp1">
<input type="text" id="inp2">
<button id="btn">+</button>
<script>
btn.onclick=function(){
var inp1=document.getElementById("inp1").value,
inp2=document.getElementById("inp2").value,
btn=document.getElementById("btn");
if(isNaN(inp1)==false && isNaN(inp2)==false){
var a=parseInt(inp1);
var b=parseInt(inp2);
var c=a+b;
alert(c);
}else{
alert("no");
}
};</script>
</body>