block-scope.js

function simpleExample(value) {
  if (value) {
    var varValue = value;
    let letValue = value;
    console.log(varValue, letValue); // value value
  }
 
  // varValue is available even though it was defined
  // in if-block because it was "hoisted" to function scope
  console.log(varValue); // value
 
  // letValue is a ReferenceError because 
  // it was defined within the if-block
  console.log(letValue); // Uncaught ReferenceError: letValue is not defined
}