blockScope.js

function blockScope() {
  if(true) {
    // I am inside the block    
    var functionScopeVariable = 'functionScopeVariable'
    const blockScopedVariable1 = 'blockScopedVariable1'
    let blockScopedVariable2 = 'blockScopedVariable2'  
  }
  
  console.log(functionScopeVariable)
  console.log(blockScopedVariable1)      
  console.log(blockScopedVariable2)
}

blockScope()

// returns
// functionScopeVariable
// Uncaught ReferenceError: blockScopedVariable1 is not defined
// at blockScope (<anonymous>:8:15)
// at <anonymous>:1:1