Variable created by const is not accessable before initialization in javaScript. But why there is no error in react create functional component

const BasicFunctionalComponent = props => {
   return (

export default BasicFunctionalComponent

const constantVariable = '**how I am initialized**?'

in example above I just create a basic functional component and after exporting it just initialized a constant variable set as a string. then I used it inside JSX above expected to go throw error ‘Cannot access ‘constantVariable’ before initialization’. but all’s good


Let’s start with a much more clear example:

const fx = () => {

// fx() // Call it here and it throws error

const v = 1

// fx() // Call it here and it's ok


The reason behind why it does not throw ReferenceError is basically because the component function is not called before the initialization of the constantVariable.