Question

What will be printed to console after executing the following code?


(function(){
  var x = y = 5;
})();

console.log("x defined? " + (typeof x !== 'undefined'));
console.log("y defined? " + (typeof y !== 'undefined'));

Cosmo · Accepted Answer

Since the statement var x = y = 3; is shorthand for the statements y = 3; and var x = y; y ends up being a global variable (since it is not preceded by the var keyword) and is therefore still in scope even outside of the enclosing function.

Cosmo · Accepted Answer

x defined? false
y defined? true

Cosmo · Answer

x defined? false
y defined? false

Cosmo · Answer

x defined? true
y defined? true

Cosmo · Answer

a syntax error will be thrown

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