This code will output 0 as output. delete operator is used to delete a property from an object. Here x is not an object it's local variable. delete operator doesn't affect local variables.

Source

• https://github.com/ganqqwerty/123-Essential-JavaScript-Interview-Question/blob/master/README.md

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var output = (function(x) {

  delete x;

  return x;

})(0);

​

console.log(output);