ES2015 ${ } and + operator on Buffer

seems like in ES2015, Template String ${ } syntax will apply toString() to a Buffer object

And under the circumstance of appending multiple strings together, + operator also doing the same thing.

let a = Buffer.from('hello')

let b = () => {
    console.log(`es6 : ${a}`) // hello
    console.log('es5 : ', a) // <Buffer 68 65 6c 6c 6f>
    console.log('es5-2 : ' + a) // hello 
    console.log(+a) // NaN
}

b()

I can't find enough information on this topic, can anyone explain this ?

via stackoverYC