check and pass the variable is empty in javascript

Question

I am trying to pass any variable is empty and alerting that this variable is empty

var foo ="ss", boo='';
        var output;
  if(!foo  || !boo) {
        output = !foo ? !boo + ' is empty';
        alert(output);
}

Answer 1

Here if statement works if foo or boo is empty. So if foo is empty alert "foo" else alert "boo"

var foo ="ss", boo='';
  if(!foo || !boo) {
  alert(!foo ? 'foo is empty' : "boo is empty");

}

Answer 2

const foo = "ss",
  boo = '';
const output = `${!foo && "foo" || !boo && "boo"} is empty`;
alert(output);

Answer 3

You are using the ternary IF operator but are missing the third (last) argument. The syntax goes CONDITION ? IF_TRUE_VALUE : ELSE_VALUE. Check the implementation below.

var foo = "ss", boo = '';
var output;
if (!foo || !boo) {
  // if foo is empty then display foo or else boo
  output = (!foo ? 'foo' : 'boo') + ' is empty';
  alert(output);
}

Answer 4

If you want to get the variable name, don't hardcode them into strings afterwards, such code is hard to maintain.
Use rather an Object to store your Key-Value pairs.
To later retrieve your key value pairs use Object.entries

const data = {foo:"ss", boo:"", bar:"zz", baz:""};

Object.entries(data).forEach(([k, v]) => v === "" && console.log(`${k} is empty`));