console-1690346926291.log

function add(x,y){
    return x + y;
}
undefined
add(10,20);
30
add();
NaN
function add(x=0,y=0){
    return x + y;
}
undefined
add();
0
add(10);
10
add(10,20);
30
var arr =[10,20,30];
undefined
arr.length;
3
arr = null;
null
arr.length;
VM331:1 Uncaught TypeError: Cannot read properties of null (reading 'length')
    at <anonymous>:1:5
(anonymous) @ VM331:1
if(arr!=null){
    console.log(arr.length);
}
undefined
if(arr){
    console.log("Array Present ", arr.length);
}
else{
    console.log("Array is Not Present");
}
VM582:5 Array is Not Present
undefined
arr;
null
arr = undefined;
undefined
if(arr){
    console.log("Array Present ", arr.length);
}
else{
    console.log("Array is Not Present");
}
VM636:5 Array is Not Present
undefined
arr=[10,20];
(2) [10, 20]
if(arr){
    console.log("Array Present ", arr.length);
}
else{
    console.log("Array is Not Present");
}
VM684:2 Array Present  2
undefined
function add(x,y){
    return x + y;
}
undefined
add();
NaN
function add(x,y){
    x = x || 0;
    y = y || 0;
    return x + y;
}
undefined
add();
0
var o = {};
undefined
o.name;
undefined