无法在javascript中获取声明的变量

var myVariable = "Hello, World!";

var globalVariable = "I am a global variable!";

function myFunction() {
  console.log(globalVariable); // This will work
}

function myFunction() {
  var localVariable = "I am a local variable!";
  console.log(localVariable); // This will work
}

console.log(localVariable); // This will result in an error

if (true) {
  let blockScopedVariable = "I am a block-scoped variable!";
  console.log(blockScopedVariable); // This will work
}

console.log(blockScopedVariable); // This will result in an error