Error handling any one can explain me this code

Question

// Pretend this is coming from a server as response let a = "Harry bhai";
a = undefined;
if (a !=undefined)
{
throw new Error('This is not undefined');
}
else

{
console.log('This is undefined');

}

Answer 1

If a is not undefind, JS crash with the error ('this is not undefined')

If you don't want program crash, surround the block with try/catch